Would you help explain the drop of total enthalpy?

samxsl · May 4, 2009, 22:06

Hi all,

I made a practice on the 2-D bending pipe flow simulation. The medium is Ideal gas with adiabatic wall. The max Mach number was about 0.28 indicating that there is no shock wave occurred. I found that the total enthalpy, total pressure and total temperature varied along the streamlines which indicated that the flow along one streamline was not isentropic. It was different from that I expected as isentropic flow. Did heat transportation and shear stress between adjacent streamlines cause the drop of total enthalpy ? I would much appreciate it if you help explain the mechanism.

Dmitry · May 6, 2009, 06:31

Hi!
Is your solution fully converged?
Maybe, viscous effects are significant in your case. For example, flow in boundary layer is not isenthropic.

samxsl · May 6, 2009, 21:45

Hi Dmitry, thanks for your reply.

The max residual level was set to be 1e-4 as by default and all the quantity were fully converged.I agree that the flow in boundary layer is not isentropic. However, quantities like total enthalpy along streamlines that did not pass through the boundary layer also varied. Do we have to consider the viscosity of ideal gas in this case?or there may be heat transfer between the streamlines

May 4, 2009, 22:06	Would you help explain the drop of total enthalpy?	#1
samxsl New Member Join Date: May 2009 Posts: 2 Rep Power: 0	Hi all, I made a practice on the 2-D bending pipe flow simulation. The medium is Ideal gas with adiabatic wall. The max Mach number was about 0.28 indicating that there is no shock wave occurred. I found that the total enthalpy, total pressure and total temperature varied along the streamlines which indicated that the flow along one streamline was not isentropic. It was different from that I expected as isentropic flow. Did heat transportation and shear stress between adjacent streamlines cause the drop of total enthalpy ? I would much appreciate it if you help explain the mechanism.

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May 6, 2009, 06:31		#2
Dmitry New Member Dmitry Join Date: Mar 2009 Posts: 7 Rep Power: 17	Hi! Is your solution fully converged? Maybe, viscous effects are significant in your case. For example, flow in boundary layer is not isenthropic.

May 6, 2009, 21:45		#3
samxsl New Member Join Date: May 2009 Posts: 2 Rep Power: 0	Hi Dmitry, thanks for your reply. The max residual level was set to be 1e-4 as by default and all the quantity were fully converged.I agree that the flow in boundary layer is not isentropic. However, quantities like total enthalpy along streamlines that did not pass through the boundary layer also varied. Do we have to consider the viscosity of ideal gas in this case?or there may be heat transfer between the streamlines