transient analysis for intake manifold systen in fluent

[arun1]

,i created one surface at the middle of the intake runners. i have done analysis in fluent the surface opening & closing with respect crank angle but in manifold valve opens & closes gradually.i had given condition for surface (created events) that at particular crank angle it should be wall & interrior , but its not in actual case..i dont want do moving mesh.is it possible do using porous media for gradually opening & closing flow,plz can u tell me about porous media set up in fluent

[arun1]

,i created one surface at the middle of the intake runners. i have done analysis in fluent the surface opening & closing with respect crank angle but in manifold valve opens & closes gradually.i had given condition for surface (created events) that at particular crank angle it should be wall & interrior , but its not in actual case..i dont want do moving mesh.is it possible do using porous media for gradually opening & closing flow,plz can u tell me about porous media set up in fluent