Thank you for your replay. I have only one cell zone including roller (zero thickness wall - moving wall boundary condition). I don't have any solid zones. I extracted solid from the fluid domain, so i only have the surfaces of roller walls inside my fluid domain. For that roller surfaces i have assigned moving wall boundary condition. (for example its like  imprints of solid roller inside the fluid domain).

I assigned the materials properties for the fluid but i am not sure whether the fluid domain is completely filled with water during the initialization ?

I am not solving the multi phase. I am solving single phase only water inside the fluid domain.

would you please help me how can fill my fluid domain with water before starting the simulation ?

Thank you in advance.

Best regards,