atmospheric boundary condition

BakedAlmonds · July 12, 2016, 03:06

Hi,

Can anyone teach me how to set up an atmospheric boundary condition for the initial condition for starccm+.

For example, the velocity will not be a uniform value but rather goverend by the atmospheric boundary condition formula.

wadeellis · July 12, 2016, 10:53

The way I usually do it is to define the boundary as a velocity inlet. Then, if I know what the velocities will be at each point, I define the velocities using a table. To do that, go to the boundary, select velocity inlet-> physical values -> velocity magnitude. Then you can select table under 'method'. You then need to define a table based on radius, time, or x y z coordinates. You can do this under tools. This will then be the velocity for each point throughout the simulation.

BakedAlmonds · July 12, 2016, 13:02

THANK YOU for the guidance!!!

What is the format for the table?
I have a velocity profile which varies with height. This can be plotted using excel so i can get U vs z but what about x and y?

wadeellis · July 12, 2016, 13:05

I do 2D simulations mostly, so I have one column as radius in meters starting at 0, then I define the other column as the velocity. This is for a v(r) table. I have not done a v(x,y,z) table before, but I assume you would just have columns for each dimension (x, y, z, and velocity).

BakedAlmonds · July 14, 2016, 09:02

Hi, how did you imported the table into starccm+?
I did: region > *region that i want* > physics values > velocity magnitude > *change to table (x,y,z)* > then i am stuck at this point.
I further into table x,y,z but there is nothing to select for table,table: data

wadeellis · July 14, 2016, 09:58

To create or import a table, go to the tools section. Under tables, select the type of table you want (in this case x,y,z). Then you can either create one in Star CCM+ or import one from a file. Make sure that the coordinates and velocity values are in columns as you will select which column contains x, y, z, and velocity.

BakedAlmonds · July 14, 2016, 15:17

thanks for the reply!!

In any case, if anyone else want to know how, can refer to this thread http://www.cfd-online.com/Forums/sta...ng-tables.html

July 12, 2016, 03:06	atmospheric boundary condition	#1
BakedAlmonds Member Almond Wong Join Date: May 2016 Posts: 68 Rep Power: 9	Hi, Can anyone teach me how to set up an atmospheric boundary condition for the initial condition for starccm+. For example, the velocity will not be a uniform value but rather goverend by the atmospheric boundary condition formula.

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July 12, 2016, 10:53		#2
wadeellis New Member Wade Join Date: Jul 2015 Posts: 24 Rep Power: 10	The way I usually do it is to define the boundary as a velocity inlet. Then, if I know what the velocities will be at each point, I define the velocities using a table. To do that, go to the boundary, select velocity inlet-> physical values -> velocity magnitude. Then you can select table under 'method'. You then need to define a table based on radius, time, or x y z coordinates. You can do this under tools. This will then be the velocity for each point throughout the simulation.

July 12, 2016, 13:02		#3
BakedAlmonds Member Almond Wong Join Date: May 2016 Posts: 68 Rep Power: 9	THANK YOU for the guidance!!! What is the format for the table? I have a velocity profile which varies with height. This can be plotted using excel so i can get U vs z but what about x and y?

July 12, 2016, 13:05		#4
wadeellis New Member Wade Join Date: Jul 2015 Posts: 24 Rep Power: 10	I do 2D simulations mostly, so I have one column as radius in meters starting at 0, then I define the other column as the velocity. This is for a v(r) table. I have not done a v(x,y,z) table before, but I assume you would just have columns for each dimension (x, y, z, and velocity).

July 14, 2016, 09:02		#5
BakedAlmonds Member Almond Wong Join Date: May 2016 Posts: 68 Rep Power: 9	Hi, how did you imported the table into starccm+? I did: region > region that i want > physics values > velocity magnitude > change to table (x,y,z) > then i am stuck at this point. I further into table x,y,z but there is nothing to select for table,table: data

July 14, 2016, 09:58		#6
wadeellis New Member Wade Join Date: Jul 2015 Posts: 24 Rep Power: 10	To create or import a table, go to the tools section. Under tables, select the type of table you want (in this case x,y,z). Then you can either create one in Star CCM+ or import one from a file. Make sure that the coordinates and velocity values are in columns as you will select which column contains x, y, z, and velocity.

July 14, 2016, 15:17		#7
BakedAlmonds Member Almond Wong Join Date: May 2016 Posts: 68 Rep Power: 9	thanks for the reply!! In any case, if anyone else want to know how, can refer to this thread http://www.cfd-online.com/Forums/sta...ng-tables.html