Frontal Area report issue

A_Payne723 · August 21, 2014, 13:54

Hi

Im trying to run some validation simulations prior to doing so aerodynamic work.

I am running a half body model of an Ahmed body but the front area report is consistently wrong. I ran the simulation anyway to see how bad the results would be and was leading to a Cd and Cl values around 1e23.

I have the frontal area report with:
units: m^2
view up: 1 0 0
normal: 0 0 1
Regions: all regions except domain (which is just ahmed body)

the frontal area im getting is .208 m^2

where a half body frontal area is .056016

flow is traveling in x direction with z as vertical

A_Payne723 · August 21, 2014, 16:52

To guarentee i had an issue i inserted a 1mx1m extruded square with an angle at the back similar to the ahmed body. Obviously the frontal area should be 1m^2 yet it is .495 according to Star-ccm+

please if anyone has any idea to what is messing up. Im on a little bit of a time crunch.

ping · August 22, 2014, 06:10

if the flow is in x then your normal vector should be in x too, ie 1,0,0 - you are measuring in z!

A_Payne723 · August 22, 2014, 23:16

thanks.

I was following a tutorial as im rather new to star-ccm+
I thought that part was weird and it is working now.

BOBBY MOB · September 5, 2021, 14:27

Hi what is view up in frontal area please explain it thanks

August 21, 2014, 13:54	Frontal Area report issue	#1
A_Payne723 New Member Andrew Payne Join Date: Apr 2014 Posts: 4 Rep Power: 12	Hi Im trying to run some validation simulations prior to doing so aerodynamic work. I am running a half body model of an Ahmed body but the front area report is consistently wrong. I ran the simulation anyway to see how bad the results would be and was leading to a Cd and Cl values around 1e23. I have the frontal area report with: units: m^2 view up: 1 0 0 normal: 0 0 1 Regions: all regions except domain (which is just ahmed body) the frontal area im getting is .208 m^2 where a half body frontal area is .056016 flow is traveling in x direction with z as vertical

August 22, 2014, 06:10		#3
ping Senior Member Ping Join Date: Mar 2009 Posts: 556 Rep Power: 20	if the flow is in x then your normal vector should be in x too, ie 1,0,0 - you are measuring in z! aditsatt likes this.

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August 21, 2014, 16:52		#2
A_Payne723 New Member Andrew Payne Join Date: Apr 2014 Posts: 4 Rep Power: 12	To guarentee i had an issue i inserted a 1mx1m extruded square with an angle at the back similar to the ahmed body. Obviously the frontal area should be 1m^2 yet it is .495 according to Star-ccm+ please if anyone has any idea to what is messing up. Im on a little bit of a time crunch.

August 22, 2014, 23:16		#4
A_Payne723 New Member Andrew Payne Join Date: Apr 2014 Posts: 4 Rep Power: 12	thanks. I was following a tutorial as im rather new to star-ccm+ I thought that part was weird and it is working now.

September 5, 2021, 14:27		#5
BOBBY MOB New Member BABAK Join Date: Jun 2021 Posts: 6 Rep Power: 5	Hi what is view up in frontal area please explain it thanks