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Showing papers on "Slip ratio published in 2020"


Journal ArticleDOI
Lin He1, Wei Ye1, Zejia He1, Ke Song2, Qin Shi1 
TL;DR: In this article, a combining sliding mode control (cSMC) approach of electric motor anti-lock braking system (emABS) is proposed to improve braking stability of battery electric vehicle (BEV).

41 citations


Journal ArticleDOI
TL;DR: In this paper, a multi-step FE modeling strategy has been proposed to predict the temperature evolution, thermo-mechanical response, surface fatigue life and wear behaviors in railway rail for multi wheel passages.

32 citations


Journal ArticleDOI
TL;DR: A fuzzy supervisor system is proposed to control the train dynamics at the appropriate operating point and estimate train longitudinal velocity and the adhesion coefficient between the wheels and rail surface to show the feasibility and validity of the presented approach.
Abstract: This article presents a supervisory model predictive control system to track the desired speed profile and simultaneously prevent the wheels from slipping in acceleration mode of electrical trains. The proposed control strategy employs field-oriented control (FOC) to control the angular speed of the wheel. Model predictive control (MPC) is used to control the longitudinal velocity of the train to track the desired speed profile and prevent the wheels from slipping by generating the desired angular velocity for the FOC. Since, it is not possible to control the longitudinal velocity and slip ratio independently, a fuzzy supervisor system is proposed to control the train dynamics at the appropriate operating point. A method is presented to estimate train longitudinal velocity and the adhesion coefficient between the wheels and rail surface. These components are vital to implement the proposed method in a real train control system. The closed loop stability of the control system has been studied. Simulations were run under different friction coefficients corresponding to real train parameters to verify the effectiveness of the proposed re-adhesion control system. The simulation results have been compared with the results of other researches to show the feasibility and validity of the presented approach.

30 citations


Journal ArticleDOI
TL;DR: A new control approach for automated drifting in consideration of how expert drivers conduct drifting is presented, capable of conducting drift maneuvers on both high friction roads and low friction roads without prior knowledge of the tire model and road friction coefficient.

22 citations


Journal ArticleDOI
TL;DR: Although the braking performance of the four-wheel electric braking system is worse than the conventional braking system at high initial braking speed, it still is able to meet the vehicle braking international standards and simplifies the braking system structure and saves cost.
Abstract: In this paper, a four-wheel electric braking system configuration is proposed for electric vehicles and its braking performance is compared with other conventional braking system configurations at different initial vehicle speeds and different road conditions in the case of emergency braking. In order to make the vehicle wheel slip ratio track the optimal slip ratio, a control method that combines sliding mode control and extended state observer is designed. Neural-network sliding mode control is designed for the driver’s braking command tracking in the normal braking condition. In order to improve braking energy recovery, a new braking torque distribution strategy is developed for the proposed four-wheel electric braking system based on the motor characteristics and vehicle dynamics. The designed braking torque distribution strategy is able to improve the energy recovery by adjusting the braking torque distribution ratio between the front and rear wheel braking torque while tracking the driver’s braking command. Numerical simulations have been conducted and the simulation results show that although the braking performance of the four-wheel electric braking system is worse than the conventional braking system at high initial braking speed, it still is able to meet the vehicle braking international standards and simplifies the braking system structure and saves cost. The proposed braking torque distribution strategy can improve energy recovery efficiency compared with the average allocation strategy and deceleration based allocation strategy. The simulation results show that the four-wheel electric braking system configuration with the proposed braking torque distribution strategy is suitable for low to medium speed light electric vehicles.

19 citations


Journal ArticleDOI
TL;DR: In this paper, the characteristics of 3D gas-liquid interfaces, flow pattern transitions, and void fraction in mini tubes were studied using virtual multi-vision experiments and numerical simulations in a 5.16mm horizontal tube with air as the dispersed phase and water as the continuous phase.

15 citations


Journal ArticleDOI
TL;DR: In this paper, a self-developed dynamic friction analyzer (TDFA) was proposed to measure the dynamic friction coefficient between tire and pavement in real-time in the lab, and the effect of parameters such as tire load, tire pressure, actual tire-pavement contact area, tire speed, and slip ratio on pavement friction were investigated.

14 citations


Journal ArticleDOI
TL;DR: In this paper, the authors measured wheel-terrain contact angles using both a newly developed apparatus and computer-vision-based algorithm to predict wheel travelling performance under high slip in order to prevent rovers from becoming stuck.

14 citations


Journal ArticleDOI
21 Jan 2020
TL;DR: This paper focuses on controlling traction for a four-wheel electric vehicle by using the longitudinal slip ratio control technique, and a control law is formulated based upon the Lyapunov stability approach to assure the sliding action.
Abstract: This paper focuses on controlling traction for a four-wheel electric vehicle by using the longitudinal slip ratio control technique. By keeping the slip ratio value inside an optimal limit, it can ...

12 citations


Posted Content
TL;DR: An end-to-end recurrent neural network that takes available raw sensors as input (IMU, wheel odometry, and motor currents), and outputs velocity estimates, and is able to estimate lateral velocity up to 15x better than the Kalman filter with the equivalent sensor input.
Abstract: Velocity estimation plays a central role in driverless vehicles, but standard and affordable methods struggle to cope with extreme scenarios like aggressive maneuvers due to the presence of high sideslip. To solve this, autonomous race cars are usually equipped with expensive external velocity sensors. In this paper, we present an end-to-end recurrent neural network that takes available raw sensors as input (IMU, wheel odometry, and motor currents) and outputs velocity estimates. The results are compared to two state-of-the-art Kalman filters, which respectively include and exclude expensive velocity sensors. All methods have been extensively tested on a formula student driverless race car with very high sideslip (10° at the rear axle) and slip ratio (~20%), operating close to the limits of handling. The proposed network is able to estimate lateral velocity up to 15x better than the Kalman filter with the equivalent sensor input and matches (0.06 m/s RMSE) the Kalman filter with the expensive velocity sensor setup.

12 citations


Journal ArticleDOI
TL;DR: In this paper, the problem of constraint control for an antilock braking system (ABS) with asymmetric slip ratio constraints is addressed. And a nonlinear backstepping control method based on barrier barrier is proposed.
Abstract: This paper is concerned with the problem of constraint control for an Antilock Braking System (ABS) with asymmetric slip ratio constraints. A nonlinear backstepping control method based on Barrier ...

Journal ArticleDOI
TL;DR: In this article, an empirical equation for slip sinkage in terms of slip ratio was developed to assess the tractive performance of a tracked vehicle, and the experimental results showed that the slip sinks increased as the slip ratio increased, but the rate of increase decreased.
Abstract: When an off-road tracked vehicle travels, shearing action and ground sinkage occur on the soil–track interface, severely affecting the tractive performance of the vehicle. Notably, ground sinkage, which is induced by the vehicle’s weight (static sinkage) and longitudinal forces in the direction of travel producing slip (slip sinkage), develops motion resistance, directly restricting the tracked vehicle’s performance. Thus, it is critical to consider both static sinkage and slip sinkage to assess the tractive performance of a tracked vehicle. In this research, model track experiments were conducted to investigate slip sinkage. The experimental results showed that the slip sinkage increased as the slip ratio increased, but the rate of increase decreased. The slip sinkage was found to increase as the density of the ground decreased and imposed vertical load increased. The experimental results were used to calculate normalized slip sinkage, and an empirical equation for slip sinkage in terms of slip ratio was developed. This equation will allow vehicle operators to predict the slip sinkage and associated motion resistance for given soil and vehicle conditions.

Journal ArticleDOI
TL;DR: In this article, an online extremum-seeking algorithm and a controller based on reachability are proposed to determine the optimal slip ratio online and reach and maintain the state until the end of braking.
Abstract: The braking process is a race against time. By controlling the wheel slip around the optimal point, the maximal friction can minimize braking distance, and it can be achieved when the tire and the vehicle reach a state named as the optimal slip ratio. The aim of this paper is to determine the optimal slip ratio online and reach and maintain the state until the end of braking. To achieve this objective, a new control system capable of estimating friction is proposed. The proposed control system consists of two main parts: an online extremum-seeking algorithm and a controller based on reachability. The former will generate the control commands for the controller, and the latter will track the provided commands. The proposed extremum-seeking algorithm is based on the bisection method with high searching efficiency, which can tolerate the measurement inaccuracy and noise to some degree. The maximal error caused by these kinds of inaccuracy has been quantized by a formula. The reachability-based controller can achieve short settling time and be insensitive to the noise; few parameter need to be tuned and each parameter has an explicit physical meaning. The stability and robustness of the control method have been proved. The effectiveness and robustness of the proposed system is illustrated by numerical simulations. The results show that the proposed method can achieve the shortest braking distance compared with other methods, even under extreme road conditions.

Journal ArticleDOI
14 Aug 2020
TL;DR: In this paper, an end-to-end recurrent neural network was proposed to estimate lateral velocity of a driverless race car with very high side-slip and slip ratio.
Abstract: Velocity estimation plays a central role in driverless vehicles, but standard, and affordable methods struggle to cope with extreme scenarios like aggressive maneuvers due to the presence of high sideslip. To solve this, autonomous race cars are usually equipped with expensive external velocity sensors. In this letter, we present an end-to-end recurrent neural network that takes available raw sensors as input (IMU, wheel odometry, and motor currents), and outputs velocity estimates. The results are compared to two state-of-the-art Kalman filters, which respectively include, and exclude expensive velocity sensors. All methods have been extensively tested on a formula student driverless race car with very high sideslip (10° at the rear axle), and slip ratio (≈20%), operating close to the limits of handling. The proposed network is able to estimate lateral velocity up to 15x better than the Kalman filter with the equivalent sensor input, and matches (0.06 m/s RMSE) the Kalman filter with the expensive velocity sensor setup.

Journal ArticleDOI
TL;DR: Continuous friction measurement equipment (CFME) has been demonstrated as an appropriate method to acquire friction around the critical slip ratio for the Pavement Friction Management (PFM) program.
Abstract: Continuous friction measurement equipment (CFME) has been demonstrated as an appropriate method to acquire friction around the critical slip ratio for the Pavement Friction Management (PFM) program...

Journal ArticleDOI
TL;DR: An integrated chassis control is proposed by explicitly incorporating both motor energy and tire slip energy in the main objective function and an semi-empirical UniTire tire slipEnergy model is proposed for derivation of the tire dissipation energy.
Abstract: Energy efficiency is extremely important for electric vehicles to improve their driving range. As the motor output energy directly acts on the tire, the tire slip energy generated by tire excessive slip will reduce the effective utilization of motor output energy, resulting in the reduction of energy efficiency, especially in the case of low friction coefficient, or even vehicle instability in some changes, such as slalom change, etc. Therefore, this paper designs an integrated chassis control and verifies the energy utilization. First, based on model predictive control (MPC), an integrated chassis controller is proposed by explicitly incorporating both motor energy and tire slip energy in the main objective function. Second, the reference control actions of the torque distribution method optimized for the motor energy, which facilitates solution-search process of MPC. Then, a semi-empirical UniTire tire slip energy model is proposed for derivation of the tire dissipation energy. Acceleration and stability tests are conducted by four in-wheel independent motor-drive electric vehicles (4WIMD-EVs) on winter proving ground, respectively. The acceleration change results show that both tire dissipation energy and motor output energy are well suppressed to achieve energy-efficient, and the energy utilization ratio of tire dissipation energy to motor output energy is only 35% to achieve stable acceleration. The slalom change verifies vehicle stability, and the results show that the slip ratio of four wheels only reaches to 0.04, and the motor output energy of four wheels is effectively utilized to generate differential yaw moment.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the influence of the inlet operating conditions to an expansion device, on the adiabatic two-phase flow development in a horizontal pipe downstream from the expansion device.
Abstract: To optimize a vertical flash tank separator, the characteristics of the flow entering the separator are required to be known. A flash tank separator improves the performance of a refrigeration cycle by separating the liquid from liquid-gas flow and providing the evaporator with only liquid refrigerant. This technique improves the effective area and enhances the heat transfer coefficient in the evaporator. This paper investigates the influence of the inlet operating conditions to an expansion device, on the adiabatic two-phase flow development in a horizontal pipe downstream from the expansion device. This work also compares three dimensional numerical simulations and experimental observations for the two-phase flow development after the expansion device in the horizontal pipe. A general trend of the two-phase flow after the expansion device was gradually developed and the expansion length was identified at less than 200 mm from the inlet. The two-phase flow behaviour was recorded using a digital camera recording the flow behaviour at the upstream and downstream of the horizontal tube. The results revealed that an increase of the mass flow rate causes an increase in the void fraction and a reduction in the slip ratio in the developed region. The simulations underestimate the expansion length and the mean difference between the experimental data and the numerical results is 8 %

Journal ArticleDOI
TL;DR: The experimental results show that the proposed braking pressure control strategy can improve the servo performance of the EMA, and the hardware in loop (HIL) experimental results indicate thatThe proposed slip ratio control strategy demonstrates a satisfactory performance in terms of stability under various runway conditions.
Abstract: This paper proposes a backstepping fuzzy sliding mode control method for the antiskid braking system (ABS) of unmanned aerial vehicles (UAVs). First, the longitudinal dynamic model of the UAV braking system is established and combined with the model of the electromechanical actuator (EMA), based on reasonable simplification. Subsequently, to overcome the higher-order nonlinearity of the braking system and ensure the lateral stability of the UAV during the braking process, an ABS controller is designed using the barrier Lyapunov function to ensure that the slip ratio can track the reference value without exceeding the preset range. Then, a power fast terminal sliding mode control algorithm is adopted to realize high-performance braking pressure control, which is required in the ABS controller, and a fuzzy corrector is established to improve the dynamic adaptation of the EMA controller in different braking pressure ranges. The experimental results show that the proposed braking pressure control strategy can improve the servo performance of the EMA, and the hardware in loop (HIL) experimental results indicate that the proposed slip ratio control strategy demonstrates a satisfactory performance in terms of stability under various runway conditions.

Journal ArticleDOI
TL;DR: In this article, the dynamics of a horizontal pipe conveying a two-phase fluid (gas and liquid) is studied, and a probabilistic model is developed considering uncertainties in three flow parameters, (1) the flow profile factor, (2) the slip ratio and (3) the vapour quality, in order to analyse the influence of these parameters on the dynamic stability and on the frequency response of the system.
Abstract: This paper is interested in the dynamics of a horizontal pipe conveying a two-phase fluid (gas and liquid), which is a problem of great regard for the oil and gas industry. The purpose of this paper is twofold. First, it introduces dimensionless coefficients that carry the information of the two-phase flow, allowing the dynamic equation to be written analogously to the equation of a single-phase fluid. Second, a probabilistic model is developed considering uncertainties in three flow parameters, (1) the flow profile factor, (2) the slip ratio and (3) the vapour quality, in order to analyse the influence of these parameters on the dynamic stability and on the frequency response of the system. The pipe is described using the linear elastic Euler–Bernoulli beam theory, and the fluid is modelled taking into account a constant tangential velocity of the flow. The coupled system is discretized by means of the finite element method, and the stochastic problem is approximated using the Monte Carlo method. The flow parameters affect greatly the system response, and different values of the critical flow velocity are obtained, depending on the level of uncertainty of the parameters.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the fluidelastic instability of a rotated triangular tube array subjected to two-phase crossflow considering the effect of the slip ratio of air-phase and water phase.

Journal ArticleDOI
TL;DR: In this article, the influence of the slip ratio, rolling speed and axle load on the adhesion coefficient between the wheel and the rail was analyzed under wet conditions using a full-scale roller rig.
Abstract: The purpose of this study is to investigate the adhesion characteristics of the wheel–rail under water and large sliding conditions. This is carried out by conducting a series of tests on a full-scale roller rig. The measured data provides an experimental base for conducting further theoretical research.,The influence of the slip ratio, rolling speed and the axle load on the adhesion coefficient between the wheel and the rail is analyzed under wet conditions using a full-scale roller rig.,From the research, it is found that the adhesion coefficient–slip ratio curve varies from the traditional theoretical description under water and large sliding conditions. Moreover, it is also observed that after the adhesion coefficient reaches the saturation point, the adhesion coefficient does not decrease, but continues to increase as the slip ratio increases.,The adhesion improvement phenomenon in this paper may provide new ideas for designing anti-skid control and braking system mechanisms for trains.,The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0236/

Journal ArticleDOI
TL;DR: In this article, a wheel-soil interaction model for a lightweight wheeled vehicle by measuring the normal stress distribution beneath the wheel was developed, which takes into account the following phenomena for the lightweight vehicles that have not been considered in the classical model.

Journal ArticleDOI
01 Apr 2020
TL;DR: With the built 1/4 vehicle braking systems based on the test bench and road, and the corresponding established models, the comparison and analysis of the simulation results of various road surfaces are conducted.
Abstract: Brake-by-wire systems are one of the key components in intelligent/unmanned vehicles that have attracted worldwide attention. Testing and evaluation of brake-by-wire systems are a significant step ...

Journal ArticleDOI
TL;DR: The results showed that the wear loss increased as the contact stress and slip ratio increased, and the increase in slip ratio had more significant effect on the reduction of retained austenite (RA) than the enlargement of contact stress due to the fact that the RA would probably be removed before the martensitic transformation occurred under the abrasive wear mechanism.
Abstract: This study aims to deeply understand the effect of contact stress and slip ratio on wear performances of bainitic rail steels. The results showed that the wear loss increased as the contact stress and slip ratio increased. Based on the surface damage morphology and microstructural analyses, it revealed that the rolling contact fatigue wear mechanism played a significant role under the low slip ratio, but the dominant wear mechanism transferred to the abrasive wear at the high slip ratio. Meanwhile, the bainitic steel specifically presented worse wear resistance under the abrasive wear mode. Compared with the influence of a slip ratio, the increase in contact stress led to severer plastic flows and contributed to the propagation of cracks. In addition, the contact stress and slip ratio had the opposite effect on the friction coefficient, that is, the friction coefficient of bainitic steels behaved the inverse proportion with the contact stress, but positive proportion with the slip ratio. At last, the increase in slip ratio had more significant effect on the reduction of retained austenite (RA) than the enlargement of contact stress due to the fact that the RA would probably be removed before the martensitic transformation occurred under the abrasive wear mechanism.

Journal ArticleDOI
TL;DR: The designed integrated coordination controller has obvious advantages in terms of tracking accuracy and body attitude stability during the course of lane change and is validated by using MATLAB/Simulink-Carsim co-simulation on different roads with conventional and severe pavement conditions.
Abstract: In order to fully explore the potential of distributed drive electric vehicle, an integrated coordination control method consists of model predictive control (MPC) and speed tracking control for trajectory tracking is proposed in this paper. Firstly, the vehicle dynamics model including the slip ratio of each wheel is established. Then, a multi-objective function of the MPC controller is established based on the principle of minimum tracking error, control vector, and control increment. And the optimal control sequences are obtained by optimizing the solution and correcting the feedback of the MPC, which satisfy both the actual kinematic constraints and the actuator performance constraints. The steering angle signal is sent to the steering motor directly, and the torque signal of each wheel which is obtained by superimposing the torque value output by the MPC controller and speed tracking controller is sent to the driving motor simultaneously. Finally, the proposed method is validated by using MATLAB/Simulink-Carsim co-simulation on different roads with conventional and severe pavement conditions. The simulation results show that the designed integrated coordination controller has obvious advantages in terms of tracking accuracy and body attitude stability during the course of lane change.

Proceedings ArticleDOI
01 Jul 2020
TL;DR: This paper focuses on the estimation of the maximum tire-road friction in the tire’s longitudinal direction, which relies on readily available on-board sensor measurements, hence it does not require additional hardware.
Abstract: This paper focuses on the estimation of the maximum tire-road friction in the tire's longitudinal direction. The proposed estimation scheme relies on readily available on-board sensor measurements, hence it does not require additional hardware. The estimation problem is divided over different subsystems. First, at the chassis motion level, the estimation of the vehicle's longitudinal speed at its center of gravity takes place. Second, based on the wheels rotational dynamics, the longitudinal tire forces and slip ratio are estimated via a state observer design. Information on the longitudinal maximum friction coefficient is then extracted using a model-based identification technique, which relies on Pacejka's Magic Formula tire model and the similarity method. Exponential convergence of the estimation error is guaranteed based on Lyapunov's stability theorem. The implementation and validation of the proposed estimation scheme are carried out in a MATLAB/Simulink ® framework via co-simulation with CarSim ® . Accelerate-then-brake scenarios are investigated at constant and variable friction levels, ranging from low to high. The obtained results demonstrate the estimator's ability to detect the maximum friction value, even at low tire slip values.

Proceedings ArticleDOI
30 Oct 2020
TL;DR: In this paper, the estimation of wheel slip ratio from vehicle and wheel velocities using a super twisting observer (STO) is proposed and validated in MATLAB/simulink model.
Abstract: Safety of a passanger is an important feature that is considered much during the design of an electric vehicle (EV) A perfect traction control technique is essential to acheive this goal Wheel slip ratio control method is widely accepted in stability control area of EV Recently different sliding mode algorithms are used for the slip ratio control, among them super twisting control (STC) is proved to be one of the efficient method For STC the estimation of wheel slip ratio is obtained by different nonlinear observers In this work for the estimation of slip ratio from vehicle and wheel velocities a super twisting observer (STO) is proposed Efficiency of the super twisting observer/controller system is validated in MATLAB/simulink model A performance comparison is made with first order sliding mode observer/STC system Results confirms the advancement of STO/STC system in speed of response, acccuracy and chattering reduction

Journal ArticleDOI
TL;DR: By introducing a road-condition observer, a model reference adaptive control (MRAC) method is proposed to overcome modeling errors and system uncertainties and to illustrate the effectiveness and robustness of the proposed method.
Abstract: This paper investigates a slip ratio control problem of a vehicle braking system in which real-time road conditions are unavailable. To overcome the nonlinearity and uncertainties, the slip ratio control problem is converted to a speed tracking control problem. By introducing a road-condition observer, a model reference adaptive control (MRAC) method is proposed to overcome modeling errors and system uncertainties. The road condition observer based on the Lyapunov theory is designed and a sliding mode observer is also constructed to estimate the unknown vehicle velocity. The asymptotic and robustness property of the adaptive controller is derived by the Popov hyperstability theory. Simulations under different conditions including different road adhesion coefficient, system uncertainties and modeling errors are provided to illustrate the effectiveness and robustness of the proposed method.

Journal ArticleDOI
TL;DR: A novel model predictive controller-based optimal slip ratio control system (MPC-OSRCS) is proposed that is verified on simulation platform and simulation results under various conditions to show the significant performance.
Abstract: The slip ratio control is an important research topic in in-wheel-motored electric vehicles (EVs). Traditional control methods are usually designed for some specified modes. Therefore, the optimal slip ratio control cannot be achieved while vehicles work under various modes. In order to achieve the optimal slip ratio control, a novel model predictive controller-based optimal slip ratio control system (MPC-OSRCS) is proposed. The MPC-OSRCS includes three parts, a road surface adhesion coefficient identifier, an operation mode recognizer, and an MPC based-optimal slip ratio control. The current working road surface is identified by the road surface adhesion coefficient identifier, and a modified recursive Bayes theorem is used to compute the matching degree between current road surfaces and reference road surfaces. The current operation state is recognized by the operation mode recognizer, and a fuzzy logic method is applied to compute the matching degree between actual operation state and reference operation modes. Then, a parallel chaos optimization algorithm (PCOA)-based MPC is used to achieve the optimal control under various operation modes and different road surfaces. The MPC-OSRCS for EV is verified on simulation platform and simulation results under various conditions to show the significant performance.

Journal ArticleDOI
TL;DR: Rodriguez et al. as mentioned in this paper used a more generic correlation for slip ratio as a function of the mixture Froud number (5 < Fr < 70), which can be used to significantly improve the prediction of volumetric fraction in flow situations where turbulent dispersion of oil in water occurs.
Abstract: In Rodriguez et al.1 an analytical expression was deduced to predict the slip ratio in dispersed oil-water flow. Although the quantitative agreement was quite good, the expression systematically underestimated the slip ratio. New experimental data of similar flows were collected in two different experimental facilities in pipes of different materials and diameters (26 mm and 82.8 mm i.d.). Oil-water flow data collected within a range of mixture Reynolds numbers from 1∙10^5 to 20∙10^6 in glass, acrylic and steel pipes with oil viscosities varying from 7 to 220 mPa.s were used to deduce a more generic correlation for slip ratio as a function of the mixture Froud number (5 < Fr < 70). The underestimation of the slip ratio was corrected. The new slip-ratio correlation can be used to significantly improve the prediction of volumetric fraction in flow situations where turbulent dispersion of oil in water occurs.