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-   -   Flow Through Bend tube of circular c/s (http://www.cfd-online.com/Forums/fluent/73412-flow-through-bend-tube-circular-c-s.html)

applemango March 8, 2010 05:52

Flow Through Bend tube of circular c/s
 
I am a beginner in Fluent..
1.)I am doing a project in IIT-B,simulating a 90 degree bend circular c/s tube of dia 8mm and length as 10cm..The fluid with which i am working is air/nitrogen..The flow through the channel is incompressible, laminar with Reynolds no 10..i have modelled a 2-D geometry in gambit and given the bcs as mass flow inlet and pressure outlet..So in Fluent while definig the bcs i give the input calculated from the Renoylds no..But im getting very low pressures of the order of 10^-5 Pa across the bend..And the product of friction factor(found out from the static pressure drop across a leng) into the renoylds no gives me the value as low as 0.16..Is there a way in which i can increase the pressure value??

2.)Also for the same geometry i have to simulate for compressible flow, with slip conditions at the boundry and in rarefied gas flow..So what r the changes i shld make...i made the following changes but i am getting very absurd result..I have expreimental data to validate my results which r no where near to that..The changes i madhe are:- i ticked the energy equations, n then ticked on the low pressure option..my bcs are mass flow inlet(which i calculte from te renyolds no) and outflow..I make operation conditions zero.. and then give initial pressure as 100pa..since my expermiental data values for Re 10 are in that range..But insipte of doing this im not getting the results..N one more thing, for slip condition what r the changes to be made?? i just cliked on the specofoed shear option in boundery conditions but since i dont hv shear stress value i leave it as 0..Is it rite a way??


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