Showing papers on "Fluid parcel published in 2014"

Fluid mechanics and hydraulics

Abstract: 1. Properties of Fluids 2. Fluid Statics 3. Hydrostatic Force on Surfaces 4. Bouyancy and Flotation 5. Translation and Rotation of Liquid Masses 6. Dimensional Analysis and Hydraulic Similitude 7. Fundamentals of Fluid Flow 8. Flow in Closed Conduits 9. Complex Pipeline Systems 10. Flow in Open Channels 11. Flow of Compressible Fluids 12. Measurement of Flow of Fluids 13. Forces Developed by Moving Fluids 14. Fluid Machinery

Considerations of Blood Properties, Outlet Boundary Conditions and Energy Loss Approaches in Computational Fluid Dynamics Modeling

Abstract: Despite recent development of computational fluid dynamics (CFD) research, analysis of computational fluid dynamics of cerebral vessels has several limitations. Although blood is a non-Newtonian fluid, velocity and pressure fields were computed under the assumptions of incompressible, laminar, steady-state flows and Newtonian fluid dynamics. The pulsatile nature of blood flow is not properly applied in inlet and outlet boundaries. Therefore, we present these technical limitations and discuss the possible solution by comparing the theoretical and computational studies.

Use of the Parcel Buoyancy Minimum (Bmin) to Diagnose Simulated Thermodynamic Destabilization. Part I: Methodology and Case Studies of MCS Initiation Environments

Abstract: A method based on parcel theory is developed to quantify mesoscale physical processes responsible for the removal of inhibition energy for convection initiation (CI). Convection-permitting simulations of three mesoscale convective systems (MCSs) initiating in differing environments are then used to demonstrate the method and gain insights on different ways that mesoscale thermodynamic destabilization can occur.Central to the method is a thermodynamic quantity Bmin, which is the buoyancy minimum experienced by an air parcel lifted from a specified height. For the cases studied, vertical profiles of Bmin using air parcels originating at different heights are qualitatively similar to corresponding profiles of convective inhibition (CIN). Though it provides less complete information than CIN, an advantage of using Bmin is that it does not require vertical integration, which simplifies budget calculations that enable attribution of the thermodynamic destabilization to specific physical processes. For a...

Modeling fluid displacement in a well system environment

Abstract: In some aspects, a one-dimensional flow model is generated. The one-dimensional flow model can represent flow of a first fluid and a second fluid in a flow path in a well system environment. The one-dimensional flow model comprises an effective diffusion coefficient model for a composite fluid volume comprising the first and second fluids. The effective diffusion coefficient model calculates an effective diffusion coefficient for the composite fluid volume based on a difference between the respective densities and viscosities of the first fluid and the second fluid.

Method of Simulation of Moving Interfaces using Geometry-Aware Volume of Fluid Method

Abstract: A method for simulating moving interface in viscous incompressible two phase flows is provided by conservation of the fluid volume and a detailed reconstruction of the fluid surface using sub-grid refinement of the level set with the volume-of-fluid method.

Newtonian heating effects in three-dimensional flow of viscoelastic fluid

Abstract: A mathematical model is constructed to investigate the three-dimensional flow of a non-Newtonian fluid. An incompressible viscoelastic fluid is used in mathematical formulation. The conjugate convective process (in which heat the transfer rate from the bounding surface with a finite capacity is proportional to the local surface temperature) in three-dimensional flow of a differential type of non-Newtonian fluid is analyzed for the first time. Series solutions for the nonlinear differential system are computed. Plots are presented for the description of emerging parameters entering into the problem. It is observed that the conjugate heating phenomenon causes an appreciable increase in the temperature at the stretching wall.

Magnetic resonance measurement of fluid dynamics and transport in tube flow of a near-critical fluid

Abstract: An ability to predict fluid dynamics and transport in supercritical fluids is essential for optimization of applications such as carbon sequestration, enhanced oil recovery, “green” solvents, and supercritical coolant systems. While much has been done to model supercritical velocity distributions, experimental characterization is sparse, owing in part to a high sensitivity to perturbation by measurement probes. Magnetic resonance (MR) techniques, however, detect signal noninvasively from the fluid molecules and thereby overcome this obstacle to measurement. MR velocity maps and propagators (i.e., probability density functions of displacement) were acquired of a flowing fluid in several regimes about the critical point, providing quantitative data on the transport and fluid dynamics in the system. Hexafluoroethane (C2F6) was pumped at 0.5 ml/min in a cylindrical tube through an MR system, and propagators as well as velocity maps were measured at temperatures and pressures below, near, and above the critical values. It was observed that flow of C2F6 with thermodynamic properties far above or below the critical point had the Poiseuille flow distribution of an incompressible Newtonian fluid. Flows with thermodynamic properties near the critical point exhibit complex flow distributions impacted by buoyancy and viscous forces. The approach to steady state was also observed and found to take the longest near the critical point, but once it was reached, the dynamics were stable and reproducible. These data provide insight into the interplay between the critical phase transition thermodynamics and the fluid dynamics, which control transport processes.

Dynamics of a small rigid body in a perfect incompressible fluid

Abstract: Presentation of the model: a rigid body immersed in an incompressible perfect fluid We consider the motion of a rigid body immersed in an incompressible perfect fluid in a regular domain Ω ⊂ R 2. S(t) F (t) Ω Ω = R 2 or is a bounded domain. The solid occupies at each instant t ≥ 0 a closed subset S(t) ⊂ Ω, and the fluid occupies F(t) := Ω \ S(t). In F(t), the fluid satisfies the incompressible Euler equation:    ∂u ∂t At the boundaries, the fluid satisfies the no-penetration/slip condition: u · n = 0 for x ∈ ∂Ω, u · n = V S · n = [h (t) + ϑ (t)(x − h(t)) ⊥ ] · n for x ∈ ∂S(t). Here: u = u(t, x) : F(t) → R 2 is the fluid velocity, p = p(t, x) : F(t) → R the pressure, n is the outer normal to the boundaries ∂Ω and ∂S(t), h(t) is the position of its center of mass (say h(0) = 0), ϑ is the angle with respect to the initial position (so ϑ(0) = 0). The dynamics of the solid is driven by the action of the pressure on its surface: m h (t) = ∂S(t) p n ds, J ϑ (t) = ∂S(t) p (x − h(t)) ⊥ · n ds, where m > 0 is the mass of the body, J > 0 denotes the moment of inertia. Remark. D'Alembert's paradox does not apply here, because it concerns fluids which are potential in R 2 , stationary and constant at infinity. In that case (only), D'Alembert's paradox states that the fluid does not influence the dynamics of the solid. Other formulations Vorticity formulation. In 2-D, the fluid part of the system can also be written ∂ t ω + (u · ∇)ω = 0 in F(t), and curl u = ω in F(t), div u = 0 in F(t), ∂S(t) u · τ ds = ∂S0 u 0 · τ ds = γ (Kelvin's law), + boundary conditions on u · n. As for the Euler equation alone, the complete system can be viewed as an equation of geodesics on an infinite dimensional Riemannian manifold, in the spirit of Arnold's work, see also Ebin-Marsden. References for the Cauchy problem Classical solutions (say at least C 1) solutions with finite energy: Ortega-Rosier-Takahashi in the …

A novel solution for fluid flow problems based on the lattice Boltzmann method

Abstract: Recently, phase separation and fluid flow problems have represented an important development in fluid dynamics, which has many important industrial applications. Lattice Boltzmann method (LBM) is the numerical method that explains the behaviour of fluid dynamics in mesoscopic scale single-component single-phase and multi-component multiphase flows. In this paper, we study the lattice Boltzmann models (LBMs) in two dimensions (2D) with nine directions (Q9), that is the D2Q9 model was used to study the phase separation and observe that the phenomenon of fluid flow in a cylinder has obstacle and square cavity. The simulation results show that fluid flows in the square cavity and in the cylinder, present phase separation of single-component multiphase fluid flow.

The velocity field due to an oscillating plate in an Oldroyd-B fluid

Abstract: Analytical solutions to the Navier–Stokes equations for non-Newtonian fluids are rare and tend to be mathematically complicated. We analytically solve Stokes’ second problem — the flow due to an infinite plate oscillating in-plane — for a viscoelastic fluid described by the Oldroyd-B constitutive relation, using mathematical techniques familiar to third- or fourth-year undergraduate students in physics, engineering, or mathematics. The solution is compared to the well-known solution of Stokes’ second problem for a Newtonian fluid to illustrate the effects of fluid elasticity on the flow, and we provide a straightforward interpretation of these effects in terms of the quality factor of the oscillations. This calculation provides a mathematically accessible introduction to non-Newtonian fluid flow that illustrates important physical effects while limiting the mathematical complications.

The Taylor-Proudman column in a rapidly-rotating compressible fluid I. energy transports

Abstract: A theoretical study is made of the steady flow of a compressible fluid in a rapidly rotating finite cylinder. Flow is generated by imposing mechanical and/or thermal disturbances at the rotating endwall disks. Both the Ekman and Rossby numbers are small. An examination is made of the energy budget for a control volume in the Ekman boundary layer. A combination of physical variables, which is termed the energy flux content, consisting of temperature and modified angular momentum, emerges to be relevant. The distinguishing features of a compressible fluid, in contrast to those of an incompressible fluid, are noted. A plausible argument is given to explain the difficulty in achieving the Taylor-Proudman column in a compressible rotating fluid. For the Taylor-Proudman column to be sustained, in the interior, it is shown that the net energy transport between the solid disk wall and the interior fluid should vanish. Physical rationalizations are facilitated by resorting to the concept of the afore-stated energy flux content.

Kinematics of Clustering

Abstract: The dynamical system for inertial particles in fluid flow has both attracting and repelling regions, the interplay of which can localize particles. In laminar flow experiments we find that particles, initially moving throughout the fluid domain, can undergo an instability and cluster into subdomains of the fluid when the flow Reynolds number exceeds a critical value that depends on particle and fluid inertia. We derive an expression for the instability boundary and for a universal curve that describes the clustering rate for all particles.

Isentropic primitive equations for the moist troposphere

Abstract: Despite the knowledge that the potential temperature of an air parcel has a dependence on its water vapour content, potential temperature is often still calculated as if the parcel were dry, assuming that this moisture dependence is negligible. We show that such a dry potential temperature approximation is not suitable for tropical regions. Moisture gradient terms are seen in the isentropic primitive equations when Exner and Montgomery functions are generalised with moist specific heat capacities, forming a contribution to the horizontal momentum tendency comparable to that by the Montgomery function. This reflects how local horizontal gradients in potential temperature created by inhomogeneous water vapour distribution are relatively significant compared to gradients created by inhomogeneous temperature, in a large-scale background of weak horizontal temperature gradient. In such an environment, water plays an active role in tropical atmospheric dynamics without the uptake or release of latent heat during phase changes. Hence, we suggest that the tropical troposphere is a place where the atmosphere can behave dynamically as a binary-component fluid at local and regional scales.

Penerapan dinamika fluida dalam perhitungan kecepatan aliran dan perolehan minyak di reservoir

Abstract: Water, oil and gas inside the earth are stored in the pores of the reservoir rock In the world of petroleum industry, calculation of volume of the oil that can be recovered from the reservoir is something important to do This calculation involves the calculation of the velocity of fluid flow by utilizing the principles and formulas provided by the Fluid Dynamics The formula is usually applied to the fluid flow passing through a well defined control volume, for example: cylinder, curved pipe, straight pipes with different diameters at the input and output, and so forth However, because of reservoir rock, as the fluid flow medium, has a wide variety of possible forms of the control volumes, hence, calculation of the velocity of the fluid flow is becoming difficult as it would involve calculations of fluid flow velocity for each control volume This difficulties is mainly caused by the fact that these control volumes, that existed in the rock, cannot be well defined This paper will describe a method for calculating this fluid flow velocity of the control volume, which consists of a combination of laboratory measurements and the use of some theories in the Fluid Dynamics This method has been proofed can be used for calculating fluid flow velocity as well as oil recovery in reservoir rocks, with fairly good accuration

Numerical Study of the Fluid Flow in a Cylindrical Hydrocyclone Separator

Abstract: This work presents a numerical study on the flow inside a gas-liquid cylindrical hydrocyclone separator. This equipment operates with a free-surface liquid film flow, which is a combination of a centrifugal and a gravitational movement originated by a tangential nozzle. The computational package ANSYS-CFX was employed to simulate the flow using an inhomogeneous Eulerian-Eulerian multiphase flow model with the free surface approach to capture the phases interface. Fluid dynamics is examined for a range of fluid viscosities and flow rates for a single-phase liquid flow at the inlet. The results of the simulations provided basis for the development of a compact mechanistic model for calculating velocity components, film thickness and other variables. This model was derived by analyzing the motion of a fluid element and then by including additional terms that represent the sudden expansion of the flow at the inlet of the cylindrical chamber. Then, the terms included and some model coefficients were calibrated using the numerical results. The outcomes of this work can be used to predict the flow dynamics in a hydrocyclone, which is a fundamental step for more complex evaluations such as estimating the separation efficiency and developing new constructive concepts for the equipment.Copyright © 2014 by ASME