I noticed that I need to set a diffusion coefficient in the incompressible model. I wondered if this should be the molecular diffusion coefficient or the turbulent diffusion coefficient. I think that it should be the molecular diffusion coefficient (which is a property of materials and does not depend on the flow field.) And turbulent diffusion coefficient is something that is associated with my turbulent closure. I know that many other models allow you to set a background turbulent diffusivity in case your turbulent closure produces a very low diffusivity value, and I wondered is there any places in SIMSCALE that we can set the background turbulent diffusion coefficient. Thank you so much!