maskForAliasedModes

returns a mask with locations of modes that will alias with a quadratic multiplication.

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Declaration

 antialiasMask = WVGeometryDoublyPeriodic.maskForAliasedModes(Nx,Ny,Nz);

Parameters

• Nx grid points in the x-direction
• Ny grid points in the y-direction
• Nz grid points in the z-direction (defuault 1)

Returns

• antialiasMask mask aliased mode

Discussion

Returns a ‘mask’ (matrices with 1s or 0s) indicating where aliased wave modes are, assuming the 2/3 anti-aliasing rule for quadratic interactions.

Technically one needs only restrict to 2/3s in each wavenumber direction. However, we prefer to maintain an isotropic effective grid size and instead restrict to a circle.

Basic usage,

  antialiasMask = WVGeometryDoublyPeriodic.maskForAliasedModes(8,8);

will return a mask that contains 1 at the locations of modes that will alias with a quadratic multiplication.