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Parabolic velocity profile in boundary layer

  • Assuming parabolic profile in boundary layer one should create an inlet boundary condition according to those assumptions.
  • One can use standard boundary condition of the type fixedValue and our custom utility setVelocityProfile computes the nonuniform velocity distribution at the inlet.
  • The equation of velocity parabolic profile in boundary layer is derived from Navier-Stokes equations,

Here 41 2 is the boundary layer thickness and 42 2 is the velocity of the main stream.


Figure: Parabolic profile

  • Utility setVelocityProfile sets the parabolic velocity profile at the inlet patch
  • The velocity profile represents the boundary layer with respect to the equation [*]
       double Umain = Upatch[patchi].x();
       forAll(faceCentres, facei)
          double fcY = faceCentres[facei].y();
          if(fcY <= L) 
             Upatch[facei].x() = (2.0*Umain/(L*L))*(L*fcY-0.5*fcY*fcY);
             Upatch[facei].x() = Umain;
  • The source code of the utility is present in the training materials in folder setVelocity.
  • Copy utility folder and compile it using wmake:

    # mkdir -p $WM_PROJECT_USER_DIR/applications/utilities
    # cp -r .../training/applications/utilities/setVelocity \

    # cd $WM_PROJECT_USER_DIR/applications/utilities/setVelocity
    # wmake

  • After a successful compilation the utility can be run from the root directory of any test case using the command setVelocityProfile.