The Zeldovich Pancake test is physically a 1D problem, but I run a 3D simulation and I choose a main axis along which the physical problem is solved ( X axis );

On the 3D simulation each 1D line along the axis X axis should have exactly the same values as all the other lines, but that is not the case, in the plot below I plot all the 1D lines along the 3D simulation and they are different!.

Simulation Parameters:

Lx = Ly = Lz = 64 Mpc/h

nx = ny = nz = 256

Reconstruction: PPMC

Riemann: HLLC

Integrator: VL

Also the Z and Y components of the velocity are non-zero!

The first suspect is the Gravitational Source, I will output and plot the potential, but it seems like for every line with an excess Y or Z velocity there is another line with the same excess in the other direction, this seems like a fluxes problem.

No Gravity