Hi I new to this nwsgroup.  I hope s.o. can help.^M^MI am interrested in modelling the effect of a hole on large tanks^Mthat contain viscous fluids ( heavy oils, etc...)^M^MI doubt the freeflow approximation can hold. So Iam looking for the^Mmathematical description of the problem involving fluid viscosity.^M^MI plan to put that into a math software in order to^Mget an idea of the speed with which things cans -could get out of hands in such a case.^M^Mthanks^M^MMarc^M