The all vanadium redox flow battery (VRFB) is a promising electrochemical energy storage technology with the potential to play an important role in future power grids. The flow-by fluid flow approach using flow channels is reducing pressure drops and pumping losses compared to the flow-through approach, but might lead to lower limiting current densities due to low electrolyte convection in the electrodes. We use COMSOL Multiphysics to investigate the effect of different fluid flow patterns in the electrodes and flow channels on the limiting current densities for flow-by VRFBs: Parallel and interdigitated flow channel setups are considered. Experimental results for planar cell setups are used for the calibration of fluid flow parameters like the hydraulic permeability and compression effects as well as for the validation of the simulations.