Delayed Stall using RANS

waseeqsiddiqui · February 6, 2019, 10:03

Hi everyone. I have been using K w SST for external flows of wing at subsonic and supersonic states at wall y plus less than 1. I have observed that stall would be delayed with this Rans turbulence model. For example, my expected stall alpha was 25 degree but my wing's CL would show a slight dip at 32 and then continuous slow decrease in CL. Isn't the CL supposed to abruptly fall after stall?
What Turbulence model do I employ for stall characteristics of a wing?

waseeqsiddiqui · February 13, 2019, 07:39

Anyone???
I tried this again.

Using RANS kw SST turbulence model for a fine grid with y plus less than 1, I modelled a flow around a delta wing at Mach 0.7. I used Pressure based Coupled Solver and parameterized the process via workbench in such a way that the angles of attack varied from -4 to 46 degree at 6 degree jumps. My analysis gave me a CL vs alpha curve that showed late stall behaviour by 32 degree and the curve is continuously decreasing after than traditional CL abrupt fall. Why is that? Is it due to the parameterized process as it uses the values of previous converged angle of attack at initialization? Or does it really happen for a delta wing?

February 6, 2019, 10:03	Delayed Stall using RANS	#1
waseeqsiddiqui Member MWRS Join Date: Apr 2018 Location: Islamabad Posts: 99 Rep Power: 8	Hi everyone. I have been using K w SST for external flows of wing at subsonic and supersonic states at wall y plus less than 1. I have observed that stall would be delayed with this Rans turbulence model. For example, my expected stall alpha was 25 degree but my wing's CL would show a slight dip at 32 and then continuous slow decrease in CL. Isn't the CL supposed to abruptly fall after stall? What Turbulence model do I employ for stall characteristics of a wing?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Stall detection in numerical simulation	Julian121	CFX	5	September 23, 2021 11:56
Using RANS in transient simulations	driu	CFX	5	October 14, 2015 07:50
RANS in integral form	siw	Main CFD Forum	0	August 17, 2010 03:18
Mapping RANS data onto an LES	christian	OpenFOAM Running, Solving & CFD	0	April 13, 2007 05:31
stall	yin	Main CFD Forum	1	May 10, 2000 03:03

February 13, 2019, 07:39		#2
waseeqsiddiqui Member MWRS Join Date: Apr 2018 Location: Islamabad Posts: 99 Rep Power: 8	Anyone??? I tried this again. Using RANS kw SST turbulence model for a fine grid with y plus less than 1, I modelled a flow around a delta wing at Mach 0.7. I used Pressure based Coupled Solver and parameterized the process via workbench in such a way that the angles of attack varied from -4 to 46 degree at 6 degree jumps. My analysis gave me a CL vs alpha curve that showed late stall behaviour by 32 degree and the curve is continuously decreasing after than traditional CL abrupt fall. Why is that? Is it due to the parameterized process as it uses the values of previous converged angle of attack at initialization? Or does it really happen for a delta wing?