Spatial transport with known scalar-dependent velocity

2 Spatial transport with known scalar-dependent velocity 

Let denote a nonnegative scalar with NDF n t,x,f). Generalizing Eq. (8.61), we will assume that the GPBE is 

As is done for advection-difFusion cases, the time step is fixed by setting an overall CFL condition  

With this value for At, the order of the convection scheme in grid cell i is determined from Eq. (8.121). 

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