setFloatPositions

Set positions of float-like particles to be advected by the model.

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Declaration

 setFloatPositions(self,x,y,z,trackedFields,options)

Parameters

• x x-coordinate location of the particles
• y y-coordinate location of the particles
• z z-coordinate location of the particles
• trackedFields strings of variable names
• advectionInterpolation (optional) interpolation method used for particle advection. “linear” (default), “spline”, “exact”
• trackedVarInterpolation (optional) interpolation method used for tracked field. “linear” (default), “spline”, “exact”

Discussion

Pass the initial positions of particles to be advected by all three components of the velocity field, (u,v,w).

Particles move between grid (collocation) points and thus their location must be interpolated. By default the advectionInterpolation is set to “linear” interpolation. For many flows this will have sufficient accuracy and allow you to place float at nearly every grid point without slowing down the model integration. However, if high accuracy is required, you may want to use cubic “spline” interpolation or even “exact” at the expense of computational speed.

You can track the value of any known WVVariableAnnotation along the particle’s flow path, e.g., relative vorticity. These values must also be interpolated using one of the known interpolation methods.

  nTrajectories = 101;
  xFloat = Lx/2*ones(1,nTrajectories);
  yFloat = Ly/2*ones(1,nTrajectories);
  zFloat = linspace(-Lz,0,nTrajectories);
 
  model.setFloatPositions(xFloat,yFloat,zFloat,'rho_total');

If a NetCDF file is set for output, the particle positions and tracked fields will automatically be written to file during integration. If you are not writing to file you can retrieve the current positions and values of the tracked fields by calling -floatPositions.