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IDProjectCategoryView StatusDate SubmittedLast Update
0003072OpenFOAMBugpublic2018-09-13 11:402018-09-16 02:14
Reportermichael2015 Assigned To 
PrioritynormalSeveritymajorReproducibilityalways
Status newResolutionopen 
Summary0003072: wrong sign in actuationDiskSource if velocity components of upstream velocity are of different sign
DescriptionHello in the actuationDiskSource the direction of the source is calculated as follows:

    E.xx() = uniDiskDir.x();
    E.yy() = uniDiskDir.y();
    E.zz() = uniDiskDir.z();

(Vcells[cells[i]]/V())*T*E) & upU;

If we assume the discdir is always pointing in the direction of the velocity (turbine is aligned with the incoming flow)
the force is not always directed in disc direction depending on the quadrant the velocity is coming from.

For cases: U1 = (-1 -1 0) , U2 = (1 -1 0), U3=(1 1 0), U4 = (-1 1 0)
 diskdir d: d1 = (-1 -1 0), d2 = (1 -1 0), d3 = (1 1 0), d4 = (-1 1 0)

E.xx = d.x
E.yy = d.y
E.zz = d.z

We get for the 4 cases:

E1 & d1 = (1 1 0), E2 & d2 = (1 1 0), E3 & d3 = (1 1 0), E4 & d4 = (1 1 0), i.e. that the force acting from the disc
is pointing alsway in the same direction for the different scenarios.

I suggest to let the force point in disc direction:

    scalar T = 2.0*upRho*diskArea_*mag(upU & uniDiskDir)*mag(upU & uniDiskDir)*a*(1 - a);

    forAll(cells, i)
    {
        Usource[cells[i]] += ((Vcells[cells[i]]/V())*T) uniDiskDir ;
    }

Would this be a valuable suggestion?

Best

Michael
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related to 0001847 closedwyldckat actuationDiskSourceTemplates.C - Calculation of Usource and sign convention 

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Issue History

Date Modified Username Field Change
2018-09-13 11:40 michael2015 New Issue
2018-09-13 23:44 wyldckat Relationship added related to 0001847