I about to simulate the movement of an aircraft over wavy surface water using VOF and sliding mesh. the lower zone which contains the water phase with waves in the surface line is stationary while the upper zone is moving (right-to-left hand side) which carries on the aircraft by the virtue of sliding mesh. My inquiry here is how can I specify the length displacement of the upper zone. Ex: if the upper and lower zone has a length of 20 meters, then the upper zone is just allowed to move exactly about 20 meters and then start the movement from the initial point.

Some parts of Ansys help mentioned that we could apply the periodic repeat condition but this solution is not valid for my simulation since we cannot specify periodic conditions at either side of both upper and lower cell zone area!