How to increase Wall shear stress at the bottom of a channel

shaheen wahab · August 24, 2018, 10:18

Hello everyone,

I am trying to run a simulation using K-w SST model in a rectangular channel and then get the Wall shear stress at the bottom. I have tried using various methods such as Spalart Allmaras, K-e Realizable with Enhanced wall treatment, Reynold's stress model, K-e Standard, K-e RNG but the values of Wall shear stress comes out in the order of -3.

The value doesn't increase under any condition. I have used the Roughness height of 0.0005m and Roughness constant of 1. I even increased the Roughness height to 10 cm just to see if there's any change in the result, but unfortunately, there was no such difference.

I have used a mesh with 10 inflation layers with a thickness of the first layer as 0.01 m.
Is there anything that is wrong in my assumptions? I would be really grateful if anyone could help me in this matter.
Thank you
With regards
Shaheen

shaheen wahab · October 3, 2018, 08:49

The problem with this was that I chose "air" instead of "water" in Cell Zone Conditions and Reference Values.

August 24, 2018, 10:18	How to increase Wall shear stress at the bottom of a channel	#1
shaheen wahab New Member Shaheen Akhtar Wahab Join Date: Aug 2018 Location: Germany/Belgium Posts: 6 Rep Power: 7	Hello everyone, I am trying to run a simulation using K-w SST model in a rectangular channel and then get the Wall shear stress at the bottom. I have tried using various methods such as Spalart Allmaras, K-e Realizable with Enhanced wall treatment, Reynold's stress model, K-e Standard, K-e RNG but the values of Wall shear stress comes out in the order of -3. The value doesn't increase under any condition. I have used the Roughness height of 0.0005m and Roughness constant of 1. I even increased the Roughness height to 10 cm just to see if there's any change in the result, but unfortunately, there was no such difference. I have used a mesh with 10 inflation layers with a thickness of the first layer as 0.01 m. Is there anything that is wrong in my assumptions? I would be really grateful if anyone could help me in this matter. Thank you With regards Shaheen

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
decomposePar problem: Cell 0contains face labels out of range	vaina74	OpenFOAM Pre-Processing	37	July 20, 2020 05:38
Measuring wall shear stress in bend pipe	liguifan	OpenFOAM	70	December 9, 2015 03:49
Water subcooled boiling	Attesz	CFX	7	January 5, 2013 03:32
WALL SHEAR STRESS	Min-Hua Wang	CFX	0	April 3, 2002 17:40
What is the detail definition of wall shear stress	zjm	FLUENT	0	January 2, 2002 07:43

October 3, 2018, 08:49		#2
shaheen wahab New Member Shaheen Akhtar Wahab Join Date: Aug 2018 Location: Germany/Belgium Posts: 6 Rep Power: 7	The problem with this was that I chose "air" instead of "water" in Cell Zone Conditions and Reference Values.