Issue plotting Cp distribution graph for an airfoil

lewis donnelly · November 12, 2019, 14:09

Evening all,

I followed a similar thread on here in order to plot a graph of the pressure coefficient against x/L (distance along airfoil surface) for a 2D airfoil. However regardless of whether I choose 'Pressure' or 'Pressure coefficient' under my y-axis scalar quantity, I get the absolute pressure along the airfoil surface.

Am I doing something wrong here as I don't understand why pressure and pressure coefficient would give me identical results?

For reference I have attached images of my results, my expected rough results and a screenshot of my command window within STAR CCM+ showing my selections.

Any help is much appreciated!

Lewis

correct pressure distribution.jpg

pressure distribution curve.jpg

command window for distribution curve.PNG

LuckyTran · November 13, 2019, 12:56

go to the way bottom of the tree and go to Tools>Field Functions>Pressure Coefficient and check the reference properties.

lewis donnelly · November 13, 2019, 14:24

Thanks for the reply!

Changing these values only seems to alter the scale of the y axis, however it still appears to be plotting the pressure as opposed to the coefficient of pressure! The graph shape is identical to absolute pressure, and I'm not too sure why this is.

November 12, 2019, 14:09	Issue plotting Cp distribution graph for an airfoil	#1
lewis donnelly New Member lewis donnelly Join Date: Nov 2019 Posts: 6 Rep Power: 7	Evening all, I followed a similar thread on here in order to plot a graph of the pressure coefficient against x/L (distance along airfoil surface) for a 2D airfoil. However regardless of whether I choose 'Pressure' or 'Pressure coefficient' under my y-axis scalar quantity, I get the absolute pressure along the airfoil surface. Am I doing something wrong here as I don't understand why pressure and pressure coefficient would give me identical results? For reference I have attached images of my results, my expected rough results and a screenshot of my command window within STAR CCM+ showing my selections. Any help is much appreciated! Lewis correct pressure distribution.jpg pressure distribution curve.jpg command window for distribution curve.PNG

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November 13, 2019, 12:56		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,761 Rep Power: 66	go to the way bottom of the tree and go to Tools>Field Functions>Pressure Coefficient and check the reference properties.

November 13, 2019, 14:24		#3
lewis donnelly New Member lewis donnelly Join Date: Nov 2019 Posts: 6 Rep Power: 7	Thanks for the reply! Changing these values only seems to alter the scale of the y axis, however it still appears to be plotting the pressure as opposed to the coefficient of pressure! The graph shape is identical to absolute pressure, and I'm not too sure why this is.