Reverse flow problem
 

Hello everyone.
I have a huge backflow problem in my case.
I am considering flow through a cube (I made a 2d model because 3d didn't work but it didn't solve the problem).
My boundary conditions: 0.01 m/s velocity inlet and default pressure outlet. Two-phase flow (mixture or VOF), with gravity on. Unfortunately, as shown in the picture, I have a strong reverse flow, which gives non-physical results - because the inlet velocity is 0.01 m/s and the reverse flow is 0.6 m/s (I can't increase the velocity inlet)
I've tried extending the outlet, fine-tuning the mesh, setting a different operational density, but nothing works. Unfortunately, I have no idea what I can do and this is an important problem for me. (With gravity off, no problem.) It is interesting that gravity "destroys" the model even when the pressure values of my substance are constant.
Has anyone encountered such a problem? the continuity equation does not converge (i try hybrid and standard initialzation).

https://drive.google.com/drive/folde...tZ?usp=sharing

It gives a google drive link with a link (case and wbpj file) , could any of you help me? In the future I will have much more complicated geometry, so I need to refine this model so that I don't have the same problems later.