[Kasikawa]

Hi,

I need to calculate the heat release rate in a infinitesimal volume, and my approach is to find the Q = m * Cp * deltaT. I am aware that I can find the heat release in Reports on FLUENT, but I need a transient and on a limited volume control result.

I was thinking about using a custom field function calculator that multiplies {2D cell volume/density} for mass, specific heat (Cp) and temperature.

But I don't know how can I set the temperature variation on a infinitesimal volume control and if my approach of using the specific heat and mass are correct too.

I've seen that there are other posts about how to calculate heat release rate on this forum, but didnt find an answer, so I'm trying this custom field function.

The main objective is to monitor the transient heat release rate and have a time x heat release rate in a point/surface of my object of study.

[MKuhn]

Maybe this could help: Try to create a own cell zone for your infinitesimal volume.

1. Mark the cells of your infinitesimal volume with the adapt tool (region adaption)
2. Seperate the cell zone based on the cells in the register (Zone --> Separate)

In this way you have the possibility to extract all values for your volume, during or after the solution process.

[Kasikawa]

Thanks for the answer!

Do you have an idea which fluent parameter should I get to have a heat release?

Because from heat equation Q = m * Cp * deltaT, I would need the variation of temperature, which I cant as far as I know (without using a second cell as reference).

I've been thinking on using Internal energy or enthalpy*density, but I'm unsure how does Fluent calculate those values.

[MKuhn]

Via Volume Report Definition you can calculate Enthalpy and internal Energy.
Or you monitor the heat flux through the boundaries between your new cell zone and the surrounding cell zones.

[Kasikawa]

MKuhn,

Monitoring through volume monitor and cell zone the way you said makes sense!

However I'm having trouble separating the cell zone. I got one cell marked, then, when I try to separa cell zone, it says "Cannot separate zones with adaption or hanging nodes". I've been searching about it, but no success yet. Any idea?

Thanks!

[MKuhn]

Use the adaption tool only to mark the desired region (in this way certain cells are stored in a register), only press the "mark" and not the "adapt"-button. Because with adapted cells in the cell zones the separation will not work.

Anyway if only one cell represent your infinitesimal volume, just define a point in the center of this volume and report/monitor the data for this point.


I don't know your physics, but with only one cell in the core area of your problem, the mesh is maybe to coarse.

[Kasikawa]

I did use the adaption tool to only mark the region, but if i'm not mistaken, I did used adapt gradient to change the mesh near the wall, before simulations.

There's many cells on the area, but I'm trying to get a really small volume (1 cell) to monitor its pressure oscilation and heat release oscilation

[AlexanderZ]

Originally Posted by Kasikawa

I did use the adaption tool to only mark the region, but if i'm not mistaken, I did used adapt gradient to change the mesh near the wall, before simulations.

There's many cells on the area, but I'm trying to get a really small volume (1 cell) to monitor its pressure oscilation and heat release oscilation

make a point to monitor from 1 cell

best regards

[Kasikawa]

AlenxaderZ,
Thanks for the answer, but that is what I've been trying (point-surface)
Is there a way to use point-surface and capture deltaTemperature?
Or by using static temperature on a point I get deltaTemperature on that cell