Hello, I read something about the pressure drop across a valve and it was specified this is a singular pressure drop equivalent to K*U²/g (Borda formula). My question is, can we used the Bernouilli formula for a permanant incompressible flow to determine the flow rate function of the pressure drop. With the introduction of a coefficient C to take into account the energy loss through the valve. The flow rate expression is Q= S*C*A(V)*(2dP/rho)^0.5 with S the surface, A(V) a coefficient function of the velocity. It appear that a valve is similar to a diaphragm used in the experimentations. Are these expressions similar ? Thank you for your help !