Showing papers on "Volume of fluid method published in 1991"

Fluid migration along growth faults in compacting sediments

Abstract: The movement of fluids up growth faults is proposed to be periodic; when faults are active they can concentrate fluid flow, but when inactive, flow is restricted Higher flow rates are predicted to be caused by fault-zone permeabilities and fluid potentials increasing at shear stresses close to the shear strength of the rock In this way, significant flow is confined to the most active sections of moving faults Since fault activity is related to sediment accumulation rates, the volume of fluid flowing up faults should be greatest when accumulation rates are high

Centrifugal rotor having flow partition

Abstract: The present invention provides a centrifugal rotor which measures and delivers a predetermined volume of fluid to a receiving chamber in the rotor. The rotor comprises a bulk fluid chamber containing a bulk amount of fluid and a metering chamber which has a predetermined volume. The bulk fluid flowing into the metering chamber fills the chamber and excess fluid flows out into an overflow chamber. Thus, a predetermined volume is obtained. This volume is delivered to the receiving chamber through an exit duct which prevents flow at the rotational speed required to fill the metering chamber but allows flow at a second, higher rotational speed. The exit duct is typically a capillary in which capillary forces prevent flow until the rotational speed is increased.

Analysis of Flow Patterns and Solidification Phenomena in the Die Casting Process

Abstract: An analysis of the flow patterns and associated solidification phenomena during the die casting process is presented In the filling stage of the die cavity, the flow patterns are predicted using the volume of fluid method These predictions are compared with experiments using water for a variety of geometries including an obstacle within the die cavity and multiple gates In the solidification analysis, an enthalpy technique on a fixed grid is used to model the phase change with convection and diffusion occurring after the cavity is filled with liquid aluminum A feature of this model is the prediction of the shape of the liquid-solid interface Emphasis is placed on the effect of velocities from the residual flow field on this interface

Net weight dispensing system and method

Abstract: A method and system for dispensing a fluid to provide a predetermined weight percent concentration of a sample material to the fluid An estimated density value for the fluid is used to determine the volume of fluid to dispense in an initial injection of fluid which is less than the total volume of fluid required to achieve the predetermined weight percent concentration A working fluid density is then determined from the volume of fluid dispensed and a measurement of the weight of the fluid dispensed The working density is then used to determine the volume of fluid to dispense in a subsequent injection Preferably, at least three fluid injections are performed, and the working density is determined after each fluid injection

Coating processes and apparatus

Abstract: Processes and apparatus for uniformly coating discrete substrates by application of a controlled volume of fluid per unit surface area of a substrate. In one aspect, the invention provides a process comprising providing a fluid reservoir; and flowing fluid from the fluid reservoir without substantial interruption through one or more fluid applicators, the fluid applied with a controlled volume per unit surface area of the substrate, said fluid flow from the reservoir commencing and terminating to provide a fluid layer up to the perimeter of the substrate. The invention also provides fluid application apparatus which enable application of a uniform fluid layer, including apparatus that provides termination of fluid flow without fluid dripping or trailing of fluid.

Numerical method for calculation of surface tension flows in arbitrary grids

Abstract: We outline a scheme to define and track interfaces in an arbitrary quadrilateral grid by making use of a single fractional volume if fluid (VOF) variable to describe the distribution of the liquid phase in a gas-liquid-particles flowfield. The present methodology, however, represents a substantial refinement over the original VOF programs in that nonorthogonal, body-fitted, and even deforming grids can be used, and the gas and liquid phased can take on totally different properties, including compressibility and incompressibility.

Volumetric fluid dispensing apparatus and method

Abstract: A fluid dispensing apparatus having no moving parts in contact with the fluid includes a fluid chamber and a measuring cup having an open top disposed in the fluid chamber. The fluid chamber is connected to a fluid source which supplies fluid to fill the chamber to a pre-determined level above the top of the measuring cup. As the fluid chamber is being filled, the fluid overflows and fills the measuring cup. A first sensor indicates when the fluid reaches the pre-determined level above the top of the measuring cup and stops the flow of fluid into the fluid chamber. A drain, which is responsive to the first sensor, drains fluid from the fluid chamber until the fluid level drops to a predetermined level below the top of the measuring cup. As the fluid level in the fluid chamber recedes, a pre-determined volume of fluid is captured in the measuring cup. A second sensor indicates when the fluid level drops to the pre-determined level below the top of the measuring cup and stops the flow of fluid from the fluid chamber. A dispensing valve, which is responsive to the second sensor, dispenses the contents of the measuring cup. A third sensor indicates when the contents of the measuring cup are dispensed and starts the flow of fluid into the fluid chamber to begin a new cycle.

Fluid flow generating apparatus

Abstract: Apparatus for generating a precision fluid flow comprises a cylinder having side and end walls forming a fluid-receiving chamber having a fluid inlet and a fluid outlet. A cylindrical piston free of engagement with the cylinder side wall is movable longitudinally into the cylinder so as to displace through the fluid outlet a volume of fluid corresponding to the volume of the piston accommodated in the chamber. The piston is formed of a material which is substantially insensitive to variations in temperature and pressure of the fluid in the chamber so that the piston rod is substantially dimensionally stable. The piston is moved relative to the chamber by a precision driving mechanism either at a constant velocity to provide a constant volumetric flow of fluid through the outlet or at a variable velocity to provide a constant fluid pressure at the outlet.

Numerical Analysis of a Single Bubble with VOF Method.

Abstract: In order to examine the feasibility of direct simulation of bubbly flows, the applicability of the VOF (volume of fluid) method to the analyses of a single rising bubble was examined in this study. Calculated bubble shapes and terminal velocities under wide ranges of Eotvos number and Morton number were compared with the experimental data summarized by Grace et al. Except for the cases when bubble shapes are spherical-cap and skirted, the VOF method could predict them well by assigning only eight cells to the bubble diameter. Hence, it was confirmed that some modification of this method will enable us to simulate bubbly flows directly under a wide-range of flow conditions. Moreover, the relation between a bubble shape and velocity distribution was examined within the ranges in which the VOF method is valid. It was found that the secondary vortex appearing in wobbling bubbles induces the velocity component normal to the bubble interface, and this velocity is one of the causes of the wobbling shape of the bubble.

A higher-order eulerian scheme for coupled advection-diffusion transport

Abstract: A new accurate high-order numerical method is presented for the coupled transport of a passive scalar (concentration) by advection and diffusion. Following the method of characteristics, the pure advection problem is first investigated. Interpolation of the concentration and its first derivative at the foot of the characteristic is carried out with a fifth-degree polynomial. The latter is constructed by using as information the concentration and its first and second derivatives at computational points on current time level t in Eulerian co-ordinates. The results are extended to coupled transport by advection and diffusion. Diffusion of the concentration takes place in parallel with advection along the characteristic. The applicability and precision of the method are demonstrated for the case of a Gaussian initial distribution of concentrations as well as for the case of a steep advancing concentration front. The results of the simulations are compared with analytical solutions and some existing methods.

A comparative study of numerical advection schemes featuring a one-step modified WKL algorithm

Abstract: A fourth-order Crowley-type advection scheme based on the multistep Warming-Kutler-Lomax (WKL) scheme is proposed in this study. This scheme utilizes a free parameter to minimize dispersion and dissipation and can be used to represent the advection of positive-definite scalars (such as moisture). Linear Fourier component analyses indicate that the fourth-order Crowley-type scheme can reproduce the features of other modified Crowley-type schemes of third order, such as the scheme of Schlesinger and the quadratic upstream interpolation. Using the free parameter, the scheme may illustrate the limitation of the Crowley-type schemes for which diffusion is required for numerical stability of advective quantity. For these schemes, formulations that preserve amplitude are inevitably associated with smaller time steps. Adding the first cross-space term into these schemes could eliminate marginal instability or overshooting in linear advection. Linear and nonlinear advection tests show that the performance...

Sampling rheometer and method

Abstract: A rheometer and a method for measuring rheological properties of a fluid material, especially in an in-line arrangement in a manufacturing process, include capturing and confining a volume of the fluid material against movement within a chamber, advancing an orifice plate having an orifice into the confined volume of the fluid material in the chamber such that the fluid material flows relative to the orifice to pass through the orifice plate, and determining the pressure in the confined volume of fluid material as the orifice plate is advanced into the chamber and through the confined volume of fluid material and the fluid material passes through the orifice, the pressure being indicative of the rheological properties being measured.

Poppet valve for high pressure fluid pump

Abstract: PURPOSE: To reduce the formation of a separated flow area by forming a passage defining surface which forms a valve passage incorporating a forward outlet end part, in a valve seat member, and by incorporating valve seat contact surface which is extended radially outward from the outlet end part of the valve passage. CONSTITUTION: When a valve element 50 of a valve 38 is slightly displaced from a close position with respect to a valve seat member 56, an annular passage 128 which is enlarged radially is defined between both contact surfaces 122, 126, and when fluid initiates its flow through the passage 58, fluid adjacent to a surface 112 flows being adjacent to a corner 118. Further, a relative static fluid pressure area is formed by defining a separate flow area 130 in an annular recess 114, and accordingly, an effective boundary area 132 caused thereby is convexly curved so that a smooth transitional flow area is formed in the flow of the fluid. Thereby it is possible to increase the volume of fluid in a low energy boundary layer.

Evaluation of fluid loss for subsurface fracturing

Abstract: The evaluation of fluid loss for subsurface fracturing is made through use of two test fracturing or "mini-frac" operations to determine formation parameters. A first mini-frac operation is performed to determine the fluid efficiency of the formation, and a second mini-frac operation is performed to determine a late time fluid leak-off coefficient. The data thus obtained are functionally related to simultaneously solve integral expressions to determine the total volume of fluid lost during pumping and the total volume of fluid lost during shut-in in response to an assumed spurt time. The fluid loss values are then functionally related to the established fluid efficiency to estimate an early time fluid leak-off coefficient. The early time fluid leak-off coefficient thus determined is then applied in a balance equation to verify the accuracy of such value in response to the assumed spurt time. The assumed spurt time may then be varied and the above fluid loss values iteratively reevaluated until the balance equation is satisfied within an acceptable range of tolerance.

Stability and chaotic advection in the eccentric Taylor problem

Abstract: Theoretically, Lagrangian chaos or chaotic advection can occur by forcing a steady, two‐dimensional velocity field with a time‐periodic perturbation. This idea has recently been confirmed experimentally by Chaiken et al.1 and Chien et al.2 In principle, chaotic advection should also occur in a three‐dimensional steady flow. To investigate this problem we constructed an eccentric Taylor–Couette apparatus with a rotating inner cylinder and a stationary outer cylinder. We obtain a 3‐D steady flow in the following way. We first create a 2‐D velocity field at small rotation rates of the inner cylinder by imposing a sufficiently large ecccentricity to obtain separated flow. (That is, an eddy in the region of largest gap is created by the separation of the fluid from the outer boundary and its reattachment downstream.) The inner cylinder rotation rate is then increased until Taylor vortices appear. The Taylor vortices modify the separated flow but do not destroy it. It is in this mixed Taylor vortex‐separated fl...