VOF Wave Forcing and Wave Damping

The VOF Waves model includes both wave forcing and wave damping capabilities.

In many VOF Wave applications, you need to simulate transient flows around bodies over a longer period. Although the flow usually takes place in a large domain, you are normally interested only in the solution in the immediate vicinity of the body. Simcenter STAR-CCM+ can reduce the size of the computational domain and thus reduce the computing effort while not compromising the accuracy and reliability of the solution. To achieve this, the solution of the 3D Navier-Stokes equations is forced towards a solution that is based on a simplified theory (or a 2D solution in a larger domain) over some distance around the body. Momentum sources only are used—no Phase sources or Turbulence sources are applied. The forcing source terms adapt the solution to the simplified solution that is imposed at the reduced domain boundary. This forcing resolves the problem of specifying boundary conditions on the reduced solution domain boundaries.

Forcing can be used to damp the upstream-propagating waves before they reach the inlet boundary, allowing long-lasting simulations to be performed on a reduced domain. Disturbances by reflections from boundaries must be eliminated, particularly when the incoming waves are irregular and possible extreme events need to be captured reliably.

See Wave Forcing.

A VOF wave can also be damped in the vicinity of selected boundaries to reduce wave oscillation near those boundaries. The damping introduces vertical resistance to the vertical motion. For example, waves that are generated by floating bodies can be damped to avoid their reflection at boundaries ([121]). However, this damping approach cannot be applied at the inlet since the incoming waves would be damped as well.

See Wave Damping.

You can apply both forcing and damping to a region or boundary. For example, you may want to apply wave forcing near an inlet where the wave shapes are known and specified, but apply wave damping at an outlet where the wave shape has developed and differs from that specified at the inlet. If both forcing and damping are applied to a cell, the result is a forcing towards the damped target wave.

Setting Up VOF Wave Forcing

To set up VOF wave forcing in a particular region or for specific boundaries in your simulation:

  1. In the Physics Conditions of the region, set the VOF Wave Zone Option to Forcing or Forcing & Damping.

    See VOF Wave Zone Option.

  2. In the Physics Values of the region, set the Forcing VOF Wave Specification.

    See Forcing VOF Wave Specification.

  3. In the Physics Conditions of the region, set the Forcing Length Specification to Region or Boundary, whichever is appropriate.

    See Forcing Length Specification.

  4. If the forcing length is applied to the entire region, in the Physics Values of the region, set the VOF Wave Forcing Length.

    See VOF Wave Forcing Length.

  5. In the Physics Conditions of each boundary, set the VOF Wave Forcing Boundary Option to specify whether to apply forcing at that particular boundary.

    If a cell is influenced by two or more forcing boundaries, only the largest of the forcing source terms is applied.

    See VOF Wave Forcing Boundary Option.

  6. If the forcing length is applied to individual boundaries, in the Physics Values of each boundary in which wave forcing is applied, set the VOF Wave Forcing Length.

    See VOF Wave Forcing Length.

Setting Up VOF Wave Damping

To set up VOF wave damping in a particular region of your simulation:

  1. In the Physics Conditions of the region, set the VOF Wave Zone Option to Damping or Forcing & Damping.

    See VOF Wave Zone Option.

  2. In the Physics Values of the region, set the VOF Wave Damping Length.

    See VOF Wave Damping Length.

  3. In the Physics Conditions of the region, set the Damping Length Specification to Region or Boundary, whichever is appropriate.

    See Damping Length Specification.

  4. If the damping length is applied to the entire region, in the Physics Values of the region, set the VOF Wave Damping Length.

    See VOF Wave Damping Length.

  5. In the Physics Conditions of each boundary, set the VOF Wave Damping Boundary Option to specify whether to apply damping in the zone before that particular boundary.

    If a cell is influenced by two or more damping boundaries, only the largest of the damping source terms is applied.

    See VOF Wave Damping Boundary Option.

  6. If the damping length is applied to individual boundaries, in the Physics Values of each boundary in which wave damping is applied, set the VOF Wave Damping Length.

    See VOF Wave Damping Length.