fvOptions_meanSupVelocityForce command¶
Syntax¶
Defined in an fvOptions dictionary in the system folder of the CFD case. Can only be applied if solver is able to handle fvOptions.
fvOptions uniformFixedValueVoidfraction;
Examples¶
momentumSource
{
type meanSupVelocityForce;
active yes;
meanSupVelocityForceCoeffs
{
seletionMode all; // all and cellZoneSet is permitted
fieldNames (U); // velocity field
twoPhase true; // refers to the number of fluid/liquid phases
alphaField alpha.water; // mandatory if twoPhase is set to true
coupled true; // refers to the presence of a particle phase
voidfractionField voidfraction; // mandatory if coupled is set to true
Ubar (1 0 0); // desired mean superficial velocity
relaxation 0.9; // optional relaxation factor;
alphaMin 0.9999; // settings will only take place in cells with alpha >= alphaMin (smoothening)
}
}
Description¶
The fvOption meanSupVelocityForce can be used to impose an average superficial velocity within a specific area (either defined by all when the whole domain is affected or the name of the according cellZoneSet), while at the same time accounting for the resulting pressure drop. The fvOption can be used for fluid/fluid, fluid/particle and fluid/fluid/particle cases, whereas Ubar can only be imposed to one of the fluid phases. Application examples are periodic channel flow situations or pumps within the computational domain. Please note that particularly for periodic channel flows instabilities might occur at the air-water interface due to the big differences in the densities. For such cases a cutoff-vlaue alphaMin has been introduced, which allows the user to restrict the affected area by means of a minimal phase fraction.
Restrictions¶
No known restrictions.