UDF for an annular disc.

alexskerhut · May 26, 2016, 15:14

Hey I have an annular disc whose radius goes from 5mm to 10mm and I need to write a UDF as a function of angle and radius in cylindrical co-ordinate system. I will use the DEFINE_PROFILE function but I am not able to understand how to in corporate the radius and the angle variation in disc.

Kindly help, I have searched a lot but not able to figure out the solution.

`e` · May 26, 2016, 20:18

Are you running Fluent with Cartesian coordinates? You can convert between cylindrical to Cartesian coordinates with (x,y) = (r cos(theta),r sin(theta)). Note: you need to account for the displacement of the circle if it's not centred about the origin.

alexskerhut · June 3, 2016, 03:27

Yes, I am running fluent with cartesian coordinates. My global coordinate system is 10mm above the centre of the annular disc and I want to define heat flux using DEFINE_PROFILE as a function of radial distance and angular position. Heat flux if of type = r - sin(theta) form multiplied by some constants. I am unable to write UDF for such function in cylindrical coordinates. Also theta is the angle measured from which of the axis. I need to measure theta in anticlockwise sense from the x axis along z axis. Please help me writing the UDF for the above function.

Please help me and thanks in Advance.

sooraj546 · December 30, 2017, 07:12

DID u find a solution for it @alexskerhut?

May 26, 2016, 15:14	UDF for an annular disc.	#1
alexskerhut New Member Alex Skerhut Join Date: Mar 2016 Posts: 10 Rep Power: 10	Hey I have an annular disc whose radius goes from 5mm to 10mm and I need to write a UDF as a function of angle and radius in cylindrical co-ordinate system. I will use the DEFINE_PROFILE function but I am not able to understand how to in corporate the radius and the angle variation in disc. Kindly help, I have searched a lot but not able to figure out the solution.

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May 26, 2016, 20:18		#2
`e` Senior Member Join Date: Mar 2015 Posts: 892 Rep Power: 18	Are you running Fluent with Cartesian coordinates? You can convert between cylindrical to Cartesian coordinates with (x,y) = (r cos(theta),r sin(theta)). Note: you need to account for the displacement of the circle if it's not centred about the origin.

June 3, 2016, 03:27		#3
alexskerhut New Member Alex Skerhut Join Date: Mar 2016 Posts: 10 Rep Power: 10	Yes, I am running fluent with cartesian coordinates. My global coordinate system is 10mm above the centre of the annular disc and I want to define heat flux using DEFINE_PROFILE as a function of radial distance and angular position. Heat flux if of type = r - sin(theta) form multiplied by some constants. I am unable to write UDF for such function in cylindrical coordinates. Also theta is the angle measured from which of the axis. I need to measure theta in anticlockwise sense from the x axis along z axis. Please help me writing the UDF for the above function. Please help me and thanks in Advance.

December 30, 2017, 07:12		#4
sooraj546 Member Join Date: Apr 2017 Location: india Posts: 96 Rep Power: 9	DID u find a solution for it @alexskerhut?