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Potential Flow Analysis

The potential flow analysis could be used to run simulations in which the velocity field is irrotational. This assumption is valid in several applications.

This analysis type is most frequently used to initialize the flow field for a simulation. It solves Laplace’s equation to compute the velocity potential from which the velocity field is derived. The flow is considered incompressible and inviscid. Potential flow is considered to be a very basic form of fluid flow. Since the flow is considered irrotational, vortices or turbulence effects cannot be modeled.

Potential flow around a cylinder

Potential flow around a cylinder

In the following, potential flow simulation setup is discussed.

Solver

For all cases, OpenFOAM® solver potentialFoam is used.

Domain

In order to perform a potential flow simulation on a given domain you have to discretize your geometry by creating a mesh. Details of CAD handling and Meshing are described in the Pre-processing section.

After a mesh is assigned to the simulation, it is possible to use domain-related entities associated with the mesh in setting up the simulation. Additionally, one can view the mesh or define new entities, e.g. a Topological Entity Set, to facilitate the simulation setup process. Details of each step are described in the following sections:

Model

Initial and boundary conditions need to be set.

Initial and boundary conditions

In this analysis type, the computational domain will be solved for two fields: pressure (p) and velocity (U). As a general rule for CFD simulations, all field conditions must be well-defined on all boundaries. Therefore, it is very important to define appropriate initial and boundary conditions for all variables on every boundary.

Important

Initial and boundary conditions must be specified for all variables on every boundary.

It is recommended to set the initial conditions close to the expected solution to avoid convergence problems. For this analysis type, variables could be initialized using the following methods:

Finally, the following boundary conditions are available for each variable:

Numerics

Numerical settings play an important role in simulation configuration. Ideally, they could enhance stability and robustness of the simulation. Since the optimal combination is not always trivial to find, default values are tried to be as meaningful and relevant as possible. However, all numerical setting are made available for users to have full control over the simulation. These settings are divided into three categories:

  • Properties

    All properties regarding the iterative solvers of velocity and pressure equations are set here. Relaxation factors, residual controls, and solver-specific tweaks are among these settings. However, depending on the solver (e.g. PIMPLE, PISO, ...), these settings will be adjusted. For each field, a Help message is provided on the platform.

  • Solver

    In this part, linear solvers used in computing each variable could be chosen separately. Upon choosing a solver, a set of preconditioners/smoothers and their tolerances become available. To assist with selecting the best solver, a Help message is provided for each field.

  • Numerical Schemes

    These schemes determine how each term in the governing equations should be discretized. Schemes categorized in the following groups:

    • Time differentiation
    • Gradient
    • Divergence
    • Laplacian
    • Interpolation
    • Surface-normal gradient

Simulation Control

The Simulation Control settings define the general controls over the simulation. Number of iterations, simulation interval, timestep size, and several other setting could be set. The following controls are available:

Result Control

Result Control allows users to define extra simulation result outputs. Each result control item provides data that requires additional calculation. The following result control items are available:

Applications

Find all of the following example applications for a potential flow analysis in the SimScale Project Library.

Disclaimer

Potential flow analysis is performed using the OPENFOAM® software. See our Third-party software section for further information.

This offering is not approved or endorsed by OpenCFD Limited, producer and distributor of the OpenFOAM software and owner of the OPENFOAM® and OpenCFD® trade marks. OPENFOAM® is a registered trade mark of OpenCFD Limited, producer and distributor of the OpenFOAM software.