Actually, with a higher mesh density and a finer timestep I got a working code.
Thank you so much for your help.
The reason I was undertaking this exercise, is to obtain a MWE for my previous post (Strain history in Newtonian flow). My aim is to implement the frobenius norm of the strain as a source term in the convection diffusion equation.
In the previous post I referred to the Oasis solver without a MWE, so it would be difficult for anyone to answer my questions or to figure out the problem myself.
I will give this implementation another attempt and maybe resubmit my question regarding “Strain history in convection diffusion equation” if I do not succeed.