Cylindrical coordinate system

nch · February 11, 2019, 09:10

Hi evertbody,

to define the pressure values at my outlets boundary conditions, I have to apply a mathematical model which deals with cylindrical coordinates and refers to a specified origin.

Does anybody know whether it is possible to set a cylindrical coordinate system in Fluent?

The mesh has been created in Icem: maybe it's possible to do it directly in Icem(?)

Thanks to whom will answer
Cheers,
Nick

LuckyTran · February 11, 2019, 09:44

Fluent still works in x,y,z but you can get cylindrical coordinates. But it may or may not help you. The question is how you actually will impose the pressure profile? Using a PROFILE text file, or udf, or what?

It should be doable using just x,y,z coordinates even if you have to deal with cylindrical coordinates as an intermediate step.

nch · February 11, 2019, 10:00

It is a mathematical model I created, based on first order differential equations which define a linear pressure drops along the three cylindrical directions starting from the origin.

I have to get each outlet face, calculate the average coordinates of its elements, and substitute the value of the respective variable in the equations, so that each outlets has its own pressure value depending on its center spatial position.

That's why I need a cylindrical coordinate system: to get the face cylindrical coordinates without converting cartesian to cylindrical each time.

nch · February 12, 2019, 06:43

Quote:

Originally Posted by LuckyTran

Fluent still works in x,y,z but you can get cylindrical coordinates. But it may or may not help you. The question is how you actually will impose the pressure profile? Using a PROFILE text file, or udf, or what?

It should be doable using just x,y,z coordinates even if you have to deal with cylindrical coordinates as an intermediate step.

So could you help me? Do you know how to set cylindrical coordinate system?

LuckyTran · February 12, 2019, 08:57

I don't care what your model is, it can be a black box.

Fluent works natively in x,y,z. If you are asking how to get cylindrical coordinates, you just go to cell zone conditions and set the axis Then there will be cylindrical coordinates.

Is that enough for you that they exist? No. You need them to do something. So that's why I ask how you are going to implement your model. Is knowing the cylindrical coordinates just once enough for you? If you tell people what do you actually need, they might be able to tell you how to do it.

You can go to solution data export or just write a PROFILE file in Fluent and it will output all the coordinates for the surfaces that you select.

Quote:

Originally Posted by nch

That's why I need a cylindrical coordinate system: to get the face cylindrical coordinates without converting cartesian to cylindrical each time.

What do you mean each time? You have a dynamic mesh? Otherwise the coordinates don't change.

nch · February 12, 2019, 18:06

I thought I had already told what I need clearly enough: I need to set a cylindrical coordinate system, refered to a specified point, in order to express elements' positions of outlet surfaces in cylindrical coordinates.

What to do with them and how, I already know. I just need cylindrical coordinates, nothing else, nothing more.

February 11, 2019, 09:10	Cylindrical coordinate system	#1
nch New Member Niccolò Join Date: Dec 2018 Posts: 19 Rep Power: 7	Hi evertbody, to define the pressure values at my outlets boundary conditions, I have to apply a mathematical model which deals with cylindrical coordinates and refers to a specified origin. Does anybody know whether it is possible to set a cylindrical coordinate system in Fluent? The mesh has been created in Icem: maybe it's possible to do it directly in Icem(?) Thanks to whom will answer Cheers, Nick

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February 11, 2019, 09:44		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,674 Rep Power: 66	Fluent still works in x,y,z but you can get cylindrical coordinates. But it may or may not help you. The question is how you actually will impose the pressure profile? Using a PROFILE text file, or udf, or what? It should be doable using just x,y,z coordinates even if you have to deal with cylindrical coordinates as an intermediate step.

February 11, 2019, 10:00		#3
nch New Member Niccolò Join Date: Dec 2018 Posts: 19 Rep Power: 7	It is a mathematical model I created, based on first order differential equations which define a linear pressure drops along the three cylindrical directions starting from the origin. I have to get each outlet face, calculate the average coordinates of its elements, and substitute the value of the respective variable in the equations, so that each outlets has its own pressure value depending on its center spatial position. That's why I need a cylindrical coordinate system: to get the face cylindrical coordinates without converting cartesian to cylindrical each time.

February 12, 2019, 18:06		#6
nch New Member Niccolò Join Date: Dec 2018 Posts: 19 Rep Power: 7	I thought I had already told what I need clearly enough: I need to set a cylindrical coordinate system, refered to a specified point, in order to express elements' positions of outlet surfaces in cylindrical coordinates. What to do with them and how, I already know. I just need cylindrical coordinates, nothing else, nothing more.