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Arbitrary Mesh Interface (cyclicAMI) Boundary Condition

NOTE: cyclicAMI boundary condition is supported by boundary type cyclicAMI, defined in the mesh file boundary:

 

 boundaryField
 {
    rotor_periodic_1 
    {
        type            cyclicAMI;
        inGroups        1(cyclicAMI);
        matchTolerance  0.1;
        transform       rotational;
        neighbourPatch  rotor_periodic_2;
        rotationAxis    (0 0 1);
        rotationCentre  (0 0 0);
        nFaces          1628;
        startFace       171370;
    }
 }

Parameter rotationAxis defines the axis in Cartesian coordinates (directional vector of the axis).

Parameter rotationCentre is any point from the axis. So, the axis is defined by its directional vector and one of its points.
cyclicAMI boundary condition is the same for all quantities (scalars, vectors, tensors):

p, U, k, omega, epsilon, T:

 boundaryField
 {
    rotor_periodic_1 
    {
          type         cyclicAMI;
    }
 }
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Multiphase cavitation

Multiphase cavitation is triggered by Multiphase cavitation check box in the TCFD menu, see figure crossref 3. It is only available for transient calculations. Upon checking, user will be offered additional options, see figure crossref 3. Unless user is familiar with Schnerr-Sauer model , we recommend using the default values. For more information on Scherr-Sauer model , see citeCavitationScherr. As opposed to previous case, Multiphase cavitation uses different solver, so results may (and probably will) slightly differ, when its triggered on. In this case, only Reference pressure is important, setting is the same as in previous case.

It is not recommend to use both Multiphase cavitation and Cavitation risk at the same time. Cavitation risk is not suitable for solver used in Multiphase cavitation mode, so its results may not be reliable. However, since Cavitation risk is post-processing, other results than its own will not be affected.

Results are delivered in the form of fields alpha.water and alpha.vapor , that contain volumetric fraction of water and vapor respectively. Also, volume of all vapor is evaluated and shown in report, see example on figure crossref 3. Beware, it shows only volume of vapor itself, not volume of all cells containing some vapor, so it is not directly comparable with volume of all cells with risk of cavitation inception from previous section.

cfd processor TCFDSource physical settings cavitation 2

Figure: When Multiphase cavitation is switched on, menu offers additional choices for coefficients used in Scherr-Sauer model

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OpenFOAM Training by CFD Support,   CFD SUPPORT,   info@cfdsupport.com    +420 212 243 883      © CFD support, s.r.o., Sokolovská 270/201, 190 00 Praha 9, Czech Republic