About the application of the external control module to change the ventilation volume（Python Scripts+external control）

[dynamism-prog]

control_input.csv
simple_tunnel_control_results.csv
simple_tunnel_devc.csv
simple_tunnel_steps.csv

At the moment I am trying to change the ventilation volume using the external control module in FDS to change the wind velocity at the same time as the FDS simulation, that is, to change the amount of wind volume.
I modified it in real time via python code
control_input.csv value, but I don't know if this modified value can be applied to fds to generate a new air volume for further simulation.
At the same time, if I want to update the control_input.csv file, fire simulation and temperature detection, and wind speed update are all real-time, how is the time processing arranged? In other words, if the FDS simulation is fast, but the Python wind speed calculation is slow, what should I do?

[drjfloyd]

Assuming that your input file has &RAMP ID='VEL_RAMP',EXTERNAL_FILE=T,INITIAL_VALUE=T/, then that ramp will take on the value in the control_input.csv file.

If you want to force FDS to wait for a new input file, then see the discussion on EXTERNAL_HEARTBEAT in the guide.

[dynamism-prog]

I may need to modify the ventilation volume, which means I don't know if I can imitate the temperature settings in the guide:
&RAMP ID='T RAMP',EXTERNAL_FILE=T,INITIAL_VALUE=0.081633/，
to write a modification to the size of the ventilation volume, something like this:&RAMP ID='VEL_RAMP', EXTERNAL_FILE=T, INITIAL_VALUE=0.5/.It's not just about controlling the start and stop of the fan.
At the same time, I would like to ask how I can change the ventilation volume at a specified time through the external control function, focusing on how to modify it at a specified time. Similar to the implementation of the Ramp function:
&HVAC ID='Duct-fan1', TYPE_ID='DUCT', VOLUME_FLOW=1.0, RAMP_ID='VF Ramp', NODE_ID='Node-fan1','Node-outletfan1'/
&RAMP ID='VF Ramp',
T=10,
F=-5/
&RAMP ID='VF Ramp',
T=20,
F=-10/

[drjfloyd]

Anything in FDS that takes a CTRL_ID or a RAMP_ID could be controlled externally. The process is:

-For any CTRL and/or RAMP in your FDS input file that you wish to compute externally add EXTERNAL_FILE=T.
-Add FDS outputs as needed for whatever computation you need to perform.
-Write the external program using whatever programming language or tool you desire. This program will need to read the required FDS outputs, compute whatever is needed to create new values for the CTRL and/or RAMP, and write the csv file that FDS will read. I can't tell you how to write this program or what language tool to use. You are the one who knows exactly what you are trying to do and who knows what programming skills you have.

The external control capability is really intended for things that would be too complex or difficult to easily accomplish with the built-in CTRL function capability in FDS. If what you need to compute is something fairly simple, doing with CTRL functions in FDS may be easier. There are some examples in 18.6 of the Users Guide.

[dynamism-prog]

Sorry, I still don't quite understand what you mean, I don't know if you can give me an example, at the moment my fds code is:
&SURF ID='INLET', VEL=-6.0, COLOR='BLUE', RAMP_V='VEL_RAMP'/
&RAMP ID='VEL_RAMP', EXTERNAL_FILE=T, INITIAL_VALUE=0.5/
I have also uploaded the csv file, can you please tell me if it is possible to modify the ventilation volume through this method, if not, please give me an example
control_input.csv

[drjfloyd]

Assuming you have told FDS on the &MISC line that control_input.csv is the name of the external file, then VEL_RAMP will take on whatever value you put in the csv file.

[dynamism-prog]

I'm sorry to trouble you again, I uploaded my fds code and control_input.csv file, currently I am running fds in cmd to simulate, but modify the data in the third column of the control_input.csv (10), the ventilation volume of the tunnel has not changed, is there a problem with my input format, or is it that the statement fds I applied does not recognize
tunnel_external_control.txt
control_input.csv