[Satyajit92]

Hello, everyone. I am studying the transport of a passive scalar in a flow field which is transient in nature. To this end, I slightly modified the icoFoam solver by including the scalar transport equation. So, the solver now solves the scalar transport equation at every time step after solving the pressure and velocity field.
To properly resolve the steep gradient of the scalar concentration near the boundary, it demands a very fine mesh especially close to the wall. However, a relatively coarser mesh gives fairly accurate result for the fluid velocity and pressure field. The requirement of fine mesh for the scalar transport is making the whole simulation computationally very expensive (because it takes a lot of iterative steps to solve the pressure field in fine mesh).
So, is there a way in OpenFOAM where the fluid velocity field and pressure field could be solved in a coarser mesh, then map the data to a finer mesh at every time step to solve the scalar transport? Any help would be greatly appreciated. Thank you