[PauliusRap]

Dear Flow3D CFD community ,

I have some trouble with a model in FLow 3D and I was hoping to get some suggestions if anyone could help me I would really appreciate it . The model that I am running is a air-lift reactor. It is basically a rectangle vertical tube that is filled with water. At the bottom of the tube is a fluid source. The fluid source supplies hot air (600K) that bubbles upwards to the external outflow from the tube. Addition of water is realised by using a pressure boundary with fluid elevation. The model has to evaluate phase change in the water. The model seems to be working (I have used a model with phase change from the examples given by flow 3D as a base). However the time step decreases significantly after 0.6 sec of simulation and the model crashes. I do get errors „Possible two-fluid velocity slip problem. Density ratio less than 10 to 1 may not be suitable for slip treatment.“ And if I turn of the slip option it says to turn velocity slip on.