[shuo]

Hi

I am reading about using sponge layers as nonreflecting boundary conditions. The implementation appears quite simple.

U^(n+1) = U^(n + 1)*(1 - delta)

where U is the solution vector and delta is the damping coefficient. The latter varies across the width of the buffer zone. I am wondering whether this B.C. requires a mean flow field as the initial condition. For example, say we want to simulate flow through a nozzle. The inlet conditions are imposed on the left while the rest of domain remains stationary with the sponge included near the nozzle exit. As the simulation begins, isn't the sponge acting as a sink while the flow is moving from left to right? I am a bit confused

Regards

Shuo