Too high drag force

dlugi91 · January 5, 2014, 13:08

I designete the drag and lift force for airfoil. I create simulation in 2d, model spalart-allmaras, Re=3000000. Air i treat as ideal gas with constant viscous. setting for turbulence is 1.5% turbulent intensity and 1m turbulent length scale. Mach number for air is 0.141 (from Re number).

Lift force after calculate is corect (5% discrepancies with proper values) but drag force isn't. I try k-e model but that don't change value of drag. I don't know what can i do to fix this.

When i look at forces raport viscous coefficient looks properly but pressure coefficient in my opinion is to high. How can i reduce it?
Or i do something wrong?

sina.sh · January 8, 2014, 05:47

Dear Dlugi

Are you set "reference value" in fluent?

dlugi91 · January 11, 2014, 10:35

i dont set reference value becouse i check it and this values are proper.

January 5, 2014, 13:08	Too high drag force	#1
dlugi91 New Member Join Date: May 2013 Posts: 10 Rep Power: 13	I designete the drag and lift force for airfoil. I create simulation in 2d, model spalart-allmaras, Re=3000000. Air i treat as ideal gas with constant viscous. setting for turbulence is 1.5% turbulent intensity and 1m turbulent length scale. Mach number for air is 0.141 (from Re number). Lift force after calculate is corect (5% discrepancies with proper values) but drag force isn't. I try k-e model but that don't change value of drag. I don't know what can i do to fix this. When i look at forces raport viscous coefficient looks properly but pressure coefficient in my opinion is to high. How can i reduce it? Or i do something wrong?

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January 8, 2014, 05:47		#2
sina.sh New Member sina Join Date: Sep 2011 Posts: 28 Rep Power: 15	Dear Dlugi Are you set "reference value" in fluent?

January 11, 2014, 10:35		#3
dlugi91 New Member Join Date: May 2013 Posts: 10 Rep Power: 13	i dont set reference value becouse i check it and this values are proper.