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#1 |
New Member
mathias kiesel
Join Date: Apr 2009
Posts: 3
Rep Power: 17 ![]() |
hello,
i'm working with ansys-cfx since few weeks and i try to simulate the pressure-distribution in a shock-tube after the origin shock and the second, wall-reflected, shock. During i'm satisfied with the calculated pressure-values after the first shock, the pressure-distribution after the reflected shock shows bad-damped oscillations i can't avoid. ![]() do you have any hints how i can improve my simulation? thanks |
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#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,870
Rep Power: 144 ![]() ![]() ![]() ![]() |
Hi,
Avoiding oscillations in shock waves is a difficult issue. I assume you are using the high-res differencing scheme? That should minimise the oscillations but still give you second order accuracy in most regions of the flow. Also what time differencing scheme are you using? Glenn Horrocks |
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#3 |
New Member
mathias kiesel
Join Date: Apr 2009
Posts: 3
Rep Power: 17 ![]() |
Hi glenn,
in my very first calculations i used second-order-euler-equations with a high-res-scheme. I got very bad oscillations behind my first shock. Changing to first order in euler equations improved the results for the first shock but with still unacceptable oscillations behind the reflected shock. Changing between high-res and upwind-scheme didn't change the results very much while using first-order-euler thanks for your answer matt |
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#4 |
Member
Join Date: Mar 2009
Posts: 44
Rep Power: 17 ![]() |
Try switching on "high speed numerics" in the advanced panel of the solver control. This enables some numerical techniques specifically aimed at dealing with shock oscillations/instabilities (such as the carbuncle effect).
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#5 |
New Member
mathias kiesel
Join Date: Apr 2009
Posts: 3
Rep Power: 17 ![]() |
Hi timon,
thank you for the hint. I will try it soon and report then about my results. thanks |
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#6 |
New Member
cfd
Join Date: Oct 2011
Posts: 17
Rep Power: 15 ![]() |
Hello,
I am new user of cfx and I want to simulate shocktube with two different gases, Is there any body could help me in defining the two different component of fluid which I have to use in this simulation? Regards Thanks |
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#7 |
Senior Member
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,208
Rep Power: 27 ![]() |
Hi
a question: does the flow behind the reflected shock wave have a total pressure bigger than the original driver gas? is it correct?
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