Pressure based solver is used when

ANSYS FLUENT 12.0 Theory Guide - 18.4.3 Pressure-Velocity Coupling Pressure-velocity coupling is achieved by using Equation ANSYS FLUENT provides the option to choose among five pressure-velocity coupling algorithms: SIMPLE, SIMPLEC, PISO, Coupled, and (for unsteady flows using the non-iterative time advancement scheme (NITA)) Fractional Step (FSM). All the aforementioned schemes, except the "coupled" scheme, are based on the predictor-corrector approach. For instructions on how to select these algorithms, see Note that SIMPLE, SIMPLEC, PISO, and Fractional Step use the pressure-based segregated algorithm, while Coupled uses the pressure-based coupled solver. The pressure-velocity coupling schemes that are applicable when using the Eulerian multiphase model are Phase Coupled SIMPLE, Multiphase Coupled, and Full Multiphase Coupled. These are discussed in detail in Segregated Algorithms SIMPLE The SIMPLE algorithm uses a relationship between velocity and pressure corrections to enforce mass conservation and to obtain the pressure field. If the momentum equation is solved with a guessed pressure field , the resulting face flux, , computed from Equation (18.4-13) Here is the under-relaxation factor for pressure (see Section , satisfies the discrete continuity equation identically during each iteration. SIMPLEC A number of variants of the basic SIMPLE algorithm are available in the literature. In addition to SIMPLE, ANSYS FLUENT offers the SIMPLEC (SIMPLE-Consistent) algorithm[...

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Although most flows in maritime applications can be modeled as incompressible, for certain phenomena like sloshing, slamming, and cavitation, this approximation falls short. For these events, it is necessary to consider compressibility effects. This paper presents the first step toward a solver for multiphase compressible flows: a single-phase compressible flow solver for perfect gases. The main purpose of this work is code verification of the solver using the method of manufactured solutions. For the sake of completeness, the governing equations are described in detail including the changes to the SIMPLE algorithm used in the incompressible flow solver to ensure mass conservation and pressure–velocity–density coupling. A manufactured solution for laminar subsonic flow was therefore designed. With properly defined boundary conditions, the observed order of grid convergence matches the formal order, so it can be concluded that the flow solver is free of coding mistakes, to the extent tested by the method of manufactured solutions. The performance of the pressure-based SIMPLE solver is quantified by reporting iteration counts for all grids. Furthermore, the use of pressure–weighted interpolation (PWI), also known as Rhie–Chow interpolation, to avoid spurious pressure oscillations in incompressible flow, though not strictly necessary for compressible flow, does show some benefits in the low Mach number range.

This paper describes a pressure-based solver based on the finite volume approach for the simulation of high-speed wet steam flows with non-equilibrium condensation. The governing consists of the system of Navier–Stokes equations for common mixture density, velocity, and enthalpy equipped with an appropriate Introduction The non-equilibrium condensation plays an important role in steam turbines working in Rankine cycle. Especially low pressure parts of turbines in nuclear power plants operate most of the time with wet-steam close or below the saturation line. Due to rapid expansion, the non-equilibrium condensation accompanied by an additional energy loss occurs. Moreover, the appearing droplets add other mechanical losses and cause erosion. Therefore, a reliable prediction of flows with non-equilibrium condensation plays an important role in the design of power plant turbines. The structure of vapor–liquid mixture is generally very complex. Larger droplets cause mainly blade erosion [1] and additional mechanical losses while tiny droplets are associated mainly with thermodynamic losses [2], which can be a considerable part of the overall losses in the last stages of steam turbines. Larger droplets require the use of two-fluid models, with each phase described by separate conservation laws and closed by inter-phase relations [3], [4]. Similar conclusion is presented in [5] also for cases with condensation at higher pressures. If thermodynamic losses are of primary interest,...

Hello! I am doing a natural convection flow! There are only Wall B.C and Symmetry B.C for my domain. I am looking at many discussions in this forum, also in the fluent manual, I am still not sure whether I choose Pressure Based Solver or Density Based Solver for my domain. Density Based Solver is suitable for the fast speed of the flow. Pressure Based Solver is suitable for low speed of the flow and the results are derived from the pressure equation, but in my simulation, it is the natural convection flow, so the important variables are only density, gravity and thermal expansion coefficient. There is no initial pressure at all, thus should I use Density Based Solver? Thank You in advance! • Ansys Blog Subscribe to the Ansys Blog to get great new content about the power of simulation delivered right to your email on a weekly basis. With content from Ansys experts, partners and customers you will learn about product development advances, thought leadership and trends and tips to better use Ansys tools.

ANSYS FLUENT 12.0 User's Guide - 26.3.1 Choosing the Pressure-Velocity Coupling Method ANSYS FLUENT provides four segregated types of algorithms: SIMPLE, SIMPLEC, PISO, and (for time-dependant flows using the Non-Iterative Time Advancement option (NITA)) Fractional Step (FSM). These schemes are referred to as the pressure-based segregated algorithm. Steady-state calculations will generally use SIMPLE or SIMPLEC, while PISO is recommended for transient calculations. PISO may also be useful for steady-state and transient calculations on highly skewed meshes. In ANSYS FLUENT, using the Coupled algorithm enables full pressure-velocity coupling, hence it is referred to as the pressure-based coupled algorithm. Pressure-velocity coupling is relevant only for the pressure-based solver. SIMPLE vs. SIMPLEC In ANSYS FLUENT, both the standard SIMPLE algorithm and the SIMPLEC (SIMPLE-Consistent) algorithm are available. SIMPLE is the default, but many problems will benefit from using SIMPLEC, particularly because of the increased under-relaxation For relatively uncomplicated problems (laminar flows with no additional models activated) in which convergence is limited by the pressure-velocity coupling, you can often obtain a converged solution more quickly using SIMPLEC. With SIMPLEC, the pressure-correction under-relaxation factor is generally set to 1.0, which aids in convergence speed-up. In some problems, however, increasing the pressure-correction under-relaxation to 1.0 can lead to...