Showing papers on "Volume of fluid method published in 1986"

Comprehensive modeling of a liquid rocket combustion chamber

Abstract: An analytical model for the simulation of detailed three-phase combustion flows inside a liquid rocket combustion chamber is presented. The three phases involved are: a multispecies gaseous phase, an incompressible liquid phase, and a particulate droplet phase. The gas and liquid phases are continuum described in an Eulerian fashion. A two-phase solution capability for these continuum media is obtained through a marriage of the Implicit Continuous Eulerian (ICE) technique and the fractional Volume of Fluid (VOF) free surface description method. On the other hand, the particulate phase is given a discrete treatment and described in a Lagrangian fashion. All three phases are hence treated rigorously. Semi-empirical physical models are used to describe all interphase coupling terms as well as the chemistry among gaseous components. Sample calculations using the model are given. The results show promising application to truly comprehensive modeling of complex liquid-fueled engine systems.

Method and apparatus for reducing the volume of fluid in a fluid cooled engine

Abstract: Rigid foam insert for decreasing the volume and weight of coolant required for the fluid jacket of a fluid cooled internal combustion engine.

On the two-roll mill problem

Abstract: In previous papers [1,2] we considered the numerical simulation of the flow of generalised Newtonian and visco-elastic liquids between contra-rotating cylinders—the so-called two-roll mill problem. In the latter case, an Oldroyd three-constant model was used to characterize the fluid properties. Here we extend the study to cover such a flow for a Phan-Thien—Tanner model, and compute the influence of elasticity on the volume of fluid passing through the nip of the rollers.

Small vibrations of a sphere in a spherical volume of viscous fluid

Abstract: Problems of the vibration of bodies in confined viscous fluids have been solved to determine the added masses and damping coefficients of rods [1–3] and floats [4–5]. The solutions of these problems, based on the use of simplifications of the boundary-layer method [4–6], are obtained analytically in general form and are in good agreement with the experimental data. However, in each specific case the possibility of using such solutions for given values of the fluid viscosity and vibration frequency must be justified either experimentally [2, 4, 5] or theoretically as, for example, in [1], where an analytic solution was obtained for concentric cylinders. The present paper offers a general solution of the problem of the small vibrations of a sphere in a spherical volume of fluid valid over a broad range of variation of the dimensionless kinematic viscosity. The limiting cases of this solution for both high and low viscosity are considered. The asymptotic expressions obtained are compared with calculations based on the analytic solution.

Lagrangian finite element method for sloshing problems the analysis of two-dimensional

Abstract: SUMMARY A new version of a numerical algorithm for the Lagrangian treatment of incompressible fluid flows with free surfaces is developed. The novel features of the present method are the adoptions of the Lagrangian finite element method and the velocity correction technique. The use of the velocity correction approach makes the computational scheme extremely simple in algorithmic structure. Hence, the present method is particularly attractive for large-scale problems. The techniques discussed here are applied to some two-dimensional sloshing problems, which may indicate the versatility and effectiveness of the present method. This paper deals in detail with a new finite element technique for the numerical solution of fluid flow problems involving free surfaces, and with the numerical analysis of two-dimensional sloshing problems. The analysis of sloshing phenomena is a very important problem of engineering significance, as exemplified by oil oscillations in large storage tanks and water oscillations in reservoirs due to earthquakes. Many theoretical and numerical analyses of sloshing problems have been carried out by many Most of them, however, are based on the potential flow theories, and cannot be applied to oil oscillations with strong viscous effects. To overcome this difficulty the present paper deals with transient motions of incompressible viscous fluid in containers. The numerical analysis of viscous fluid flow problems involving free surfaces is very complicated. There are two reasons for this. First, the position of the free surface varies with time in a manner not known a priori, and this fact prevents the analysis from being completely straightforward. Hence, there must be some means of tracking the position of the free surface. Secondly, the accurate free surface boundary condition must be imposed. In solving such difficult problems the finite element method combined with the Lagrangian description can be applied effectively. Two basic viewpoints are generally considered in discretizing a fluid by a finite difference or finite element method. The first is the Eulerian description, which treats the mesh as a fixed reference frame through which the fluid moves. The second is known as the Lagrangian description, in which the mesh of grid points is embedded in the fluid and moves with it. In the numerical analysis of fluid flows with free surface, a method in which the fluid is described by an Eulerian representation and the free surface is described by a Lagrangian representation is widely employed.'-" In such methods it is difficult to solve problems involving complicated free surface structure. Furthermore, it is necessary to discretize the fluid domain at each time step according to the profile of the free

Numerical Solution of Nonlinear Advection Diffusion Problems

Abstract: Mathematical formulation of weather prediction problems often gives rise to sets of coupled nonlinear partial differential equations which describe the interplay between the dynamic processes of advection, udjustment, and diffusion. In general, such systems of nonlinear equations are solved using numerical techniques. In this paper we consider a nonlinear singularly perturbed advection diffusion problem. Employing the usual Newton iteration method we derive an approximate linear advection diffusion problem and discuss some practical numerical methods for solving it.