Attempt of a numerical Navier-Stokes calculation

Posted 9 years ago
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 I tried to calculate, with NDSolve, numerically the velocity field of the two-dimensional jet; that is, fluid flowing from a hole (actually a slot) in a wall into a patch of fluid initially at rest. Originally, I wanted to post here the notebook; but it came out als FullForm, so it was rather long and (I think) difficult to read. So I attached it. After starting the program, I got several messages; a final one reads:NDSolveValue::nlnum: The function value {<<1>>} is not a list of numbers with dimensions {675} at {t,p[x,y,t],u[x,y,t],v[x,y,t],(p^(0,0,1))[x,y,t],(u^(0,0,1))[x,y,t],(v^(0,0,1))[x,y,t]} = {0.0001,<<5>>,{{0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.},{0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.},<<12>>,{0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.}}}. >>Apparently, the error reported with this message prohibited the program from running.I do not understand the message. Can anybody tell me what type of error possibly happened in the program, and what is to be done to avoid it ? Is it possible to analyze the NDSolve process so that one can explitcitly arrive at the point where the error occurs ? Attachments:
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Posted 9 years ago
 There are two messages "insufficient number of boundary conditions". I tested the problem with Burger's equation for two spacial dimensions; There, these messages appear as well, but don't prohibit the program from running. I don't know whether missing boundary conditions (which of course must be cared for) can lead to the problem announced by the message NDSolve::nlnum.
Posted 9 years ago
 It's usually better to diagnose a problem from the first warning message, not the last.
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