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Stagnation enthapy loss in subsonic adiabatic flow using RANS CFD |
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July 5, 2017, 04:55 |
Stagnation enthapy loss in subsonic adiabatic flow using RANS CFD
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#1 |
New Member
Peter
Join Date: Nov 2013
Posts: 4
Rep Power: 12 |
A plate problem is used here, Ma=0.1466, Re=6.68E6, T=286.72.
A RANS solver is used here with Jameson central scheme and artificial dissipation, RK solver. Flow is steady and fully turbulent. NASA turbulence verification plate mesh is used(about 500*300 mesh points). Viscous adiabatic wall BC, subsonic inflow and outflow BC and farfield BC are imposed on mesh boundaries. According to aerodynamic theory, the total enthapy of adiabatic flow should be constant. But in our reaults, the total enthapy of free stream is 290125(SI dimension) and total enthapy in the flow field is about 290300 to 282000(different value at each mesh point) which means total enthapy loss at some locations. Does anyone have knowledge about why this happens? |
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July 5, 2017, 05:11 |
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#2 | |
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Filippo Maria Denaro
Join Date: Jul 2010
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Quote:
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July 5, 2017, 20:47 |
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#3 |
New Member
Peter
Join Date: Nov 2013
Posts: 4
Rep Power: 12 |
Hi Denaro, thank you for looking at this. I need to use stagnation enthapy for later calculation of some other variables so I am trying to figure out whether CFD can reflect the physics and calculate stagnation enthapy in the right way. Although CFD is viscous and dissipative, it is adibatic, so stagnation enthapy should be constant.
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July 6, 2017, 02:51 |
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#4 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,773
Rep Power: 71 |
If you consider the Crocco theorem, the assumptions are that the flow has no dissipative effects (stress and heat transfer) and is steady. The total enthaply will obey the relation
Grad H + (curl v) x v =T Grad s Furthermore, do not forget that in your turbulence model, the energy has the unresolved terms modelled as additional dissipation-like |
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