Radka Keslerová

Numerical simulations of flow through channels with T-junction

The paper deals with numerical solution of laminar and turbulent flows of Newtonian and non-Newtonian fluids in branched channels with two outlets. Mathematical model of the flow is based on the Reynolds averaged Navier-Stokes equations for the incompressible fluid. In the turbulent case, the closure of the system of equations is achieved by the explicit algebraic Reynolds stress (EARSM) turbulence model. Generalized non-Newtonian fluids are described by the power-law model. The governing equations are solved by cell-centered finite volume schemes with the artificial compressibility method; dual time scheme is applied for unsteady simulations. Channels considered in presented calculations are of constant square or circular cross-sections. Numerical results for laminar flow of non-Newtonian fluid are presented. Further, turbulent flow through channels with perpendicular branch is simulated. Possible methods for setting the flow rate are discussed and numerical results presented for two flow rates in the branch.

Numerical modelling of incompressible flows for Newtonian and non-Newtonian fluids

This paper deals with numerical solution of two-dimensional and three-dimensional steady and unsteady laminar incompressible flows for Newtonian and non-Newtonian shear thickening fluids flow through a branching channel. The mathematical model used in this work is the generalized system of Navier-Stokes equations. The right hand side of this system is defined by the power-law model. The finite volume method combined with artificial compressibility method is used for numerical simulations of generalized Newtonian fluids flow. Numerical solution is divided into two parts, steady state and unsteady. Steady state solution is achieved for t->~ using steady boundary conditions and followed by steady residual behaviour. For unsteady solution high artificial compressibility coefficient @b^2 is considered. An artificial compressibility method with a pulsation of the pressure in the outlet boundary is used.

Numerical Simulations of Incompressible Laminar Flow for Newtonian and Non-Newtonian Fluids

This paper deals with numerical solution of two dimensional and three dimensional laminar incompressible flows for Newtonian and non-Newtonian fluids through a branching channel. One could describe these problems using Navier-Stokes equations and continuity equation as a mathematical model using two different viscosities. The unsteady system of Navier-Stokes equations modified by unsteady term in continuity equation (artificial compressibility method) is solved by multistage Runge-Kutta finite volume method. Steady state solution is achieved for t → ∞ and convergence is followed by steady residual behaviour. For unsteady solution high compressibility coefficient β2 is considered. The numerical results for two and three dimensional cases of flows in the branching channel for Newtonian and non-Newtonian fluids are presented and compared.

Numerical solution of laminar incompressible generalized Newtonian fluids flow

This paper deals with the numerical solution of laminar viscous incompressible flows for generalized Newtonian fluids in the branching channel. The generalized Newtonian fluids contain Newtonian fluids, shear thickening and shear thinning non-Newtonian fluids. The mathematical model is the generalized system of Navier-Stokes equations. The finite volume method combined with an artificial compressibility method is used for spatial discretization. For time discretization the explicit multistage Runge-Kutta numerical scheme is considered. Steady state solution is achieved for t?∞ using steady boundary conditions and followed by steady residual behavior. For unsteady solution a dual-time stepping method is considered. Numerical results for flows in two dimensional and three dimensional branching channel are presented.

Numerical Simulation of Viscous and Viscoelastic Fluids Flow by Finite Volume Method

This paper deals with the numerical modeling of steady incompressible laminar flows of viscous and viscoelastic fluids. The governing system of the equations is based on the system of balance laws for mass and momentum for incompressible fluid. Two models for the stress tensor are tested. The models used in this study are generalized Newtonian model with power-law viscosity model and Oldroyd-B model with constant viscosity. The numerical results for these models are presented.

Numerical solution of viscous and viscoelastic fluids flow through the branching channel by finite volume scheme

This work deals with the numerical modelling of steady flows of incompressible viscous and viscoelastic fluids through the three dimensional channel with T-junction. The fundamental system of equations is the system of generalized Navier-Stokes equations for incompressible fluids. This system is based on the system of balance laws of mass and momentum for incompressible fluids. Two different mathematical models for the stress tensor are used for simulation of Newtonian and Oldroyd-B fluids flow. Numerical solution of the described models is based on cetral finite volume method using explicit Runge-Kutta time integration.

Numerical study of steady and unsteady flow for power-law type generalized Newtonian fluids

This work deals with the numerical solution of laminar incompressible viscous flow for generalized Newtonian fluids in a branching channel. The governing system of equations is the system of generalized Navier–Stokes equations for incompressible viscous fluids flow. Generalized Newtonian fluids can be divided to two parts: shear thickening fluids and shear thinning fluids. Newtonian fluids are the special case with constant viscosity. For a viscosity function a power-law model is used. Numerical solution of the described model is based on cell-centered finite volume method using explicit Runge–Kutta time integration. The time-marching system of equations with steady boundary conditions is solved by finite volume method in conjunction with an artificial compressibility method. For the time integration an explicit multistage Runge–Kutta method of the second order of accuracy is used. In the case of unsteady computation two numerical methods are considered, artificial compressibility method and dual-time stepping method. Numerical results obtained by these methods are presented and compared.

Numerical modeling of the flow structures in the channels with T-junction

The work deals with the numerical simulations of a 3D incompressible viscous turbulent flow in the branched channels with circular cross section. The mathematical model is based on the unsteady Reynolds averaged Navier-Stokes (URANS) equations with the explicit algebraic Reynolds stress (EARSM) turbulence model. The resulting set of partial differential equations is then solved by artificial compressibility method in dual time in the finite volume formulation. The flow through the round branched channel with branch perpendicular to the main channel (T-junction) is considered. Diameter of the main channel is 50mm and diameter of the branch is 32mm. Different combinations of inlets and outlets and different flow rates are studied.

Numerical simulation of steady and unsteady flow for generalized Newtonian fluids

This work presents the numerical solution of laminar incompressible viscous flow in a three dimensional branching channel with circle cross section for generalized Newtonian fluids. The governing system of equations is based on the system of balance laws for mass and momentum. Numerical solution is based on cetral finite volume method using explicit Runge- Kutta time integration. In the case of unsteady computation artificial compressibility method is considered.

Numerical Simulation of 3D Flow of Viscous and Viscoelastic Fluids in T-Junction Channel

This paper is interested in the numerical simulation of steady flows of laminar incompressible viscous and viscoelastic fluids through the channel with T-junction. The flow is described by the system of generalized incompressible Navier-Stokes equations. For the different choice of fluids model the different model of the stress tensor is used, Newtonian and Oldroyd-B models. Numerical tests are performed on three dimensional geometry, a branched channel with one entrance and two outlet parts. Numerical solution of the described models is based on cell-centered finite volume method using explicit Runge-Kutta time integration.