In a calculation region, there are two zones: solid and liquid. The solid could not be treated as wall due to the problem requirement. I tried to treat it as interior, but warning shows the adjacient materials are different. I do not know wether Fluent could treat it as solid and liquid interface. Anyone has experience about this kind of problem?

if a solid exists next to a fluid and the nodes at the interface are shared a wall is automatically created so one has a wall and the other its shadow wall. Can only be interior if materials are the same, unless multiphase/transient problem such as for mixing.