Setting up Surface Sensitivity Filter and Morpher Displacement

For the optimized surface, you define a morpher displacement, which is calculated using the adjoint surface sensitivity field, surface sensitivity filter, and steepest descent constant.

To ensures a smooth deformation on the Wall_Adjoint, you assign the Global Filter Radius as a surface sensitivity filter.

  1. Right-click the Regions > Fluid > Boundaries > Wall_Adjoint > Physics Values > Surface Sensitivity Filter Parameters node and set Filter Option to Global Filter Radius.
To prevent the deformation on the boundary Wall:
  1. Select the Regions > Fluid > Boundaries > Wall > Physics Values > Surface Sensitivity Filter Parameters node and set Filter Option to Excluded Surface.
The steepest descent constant controls the amplitude of the surface deformation introduced at each optimization cycle. It is chosen as a balance between fast optimization progress, stability of the optimization algorithm and acceptable geometrical deformation of the volume mesh. You can derive the steepest descent constant from the allowable deformation and the maximum absolute value of the smoothed surface sensitivity field. To reduce the defined adjoint cost function, you set a negative number. In this tutorial, the steepest descent constant is set to -1.0E-3.
  1. To define the steepest descent constant, right-click Automation > Parameters and select New > Scalar.
  2. Rename the parameter Scalar to SteepestDescentConstant and set Value to -1.0e-3.
After creating these two factors, the deformation field is defined through a field function using the surface sensitivity.
  1. Right-click the Automation > Field Functions node and select New > Vector.
  2. Rename the field function User Field Function 1 to Deformation Field.
  3. Select the Deformation Field node and set the properties as follows:
    Property Setting
    Function Name DeformationField
    Dimensions Length
    Definition 
    $${CumulativeMorpherDisplacement}+${SteepestDescentConstant}*$${Adjoint1::Surface Sensitivity}
To assign the optimization deformation to the boundary Wall_Adjoint:
  1. Select the Regions > Fluid > Boundaries > Wall_Adjoint > Physics Conditions > Morpher Specification node and set Specification to Displacement.
  2. To assign the deformation to the boundary, select the Wall_Adjoint > Physics Values > Morpher Displacement node and set the following properties:
    Property Setting
    Method Field Function
    Vector Function Deformation Field
  3. Save simulation.