# I can't find 'convective heat flux' on 'result control' in my simulation

**URL:** <https://www.simscale.com/forum/t/i-cant-find-convective-heat-flux-on-result-control-in-my-simulation/101120>\
**Category:** Project Support\
**Created:** [June 7, 2026, 9:39am UTC](https://www.simscale.com/forum/t/i-cant-find-convective-heat-flux-on-result-control-in-my-simulation/101120 "2026-06-07T09:39:22Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![shinynimij](https://www.simscale.com/forum/letter_avatar/shinynimij/32/5_5575768a8748004e209b776fc1b2916d.png) [@shinynimij](https://www.simscale.com/forum/u/shinynimij)\
**Post date:** [June 7, 2026, 9:39am UTC](https://www.simscale.com/forum/t/i-cant-find-convective-heat-flux-on-result-control-in-my-simulation/101120/1 "2026-06-07T09:39:22Z")

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Hello dear community, I am using SimScale through the Academic Program for a simple physics research project on natural convection and heat transfer between two parallel acrylic plates.

I need to extract the **wall heat flux** on the acrylic plate surface to compare the simulation results with a theoretical conduction model and calculate the Nusselt number. However, I cannot find **Convective Wall Heat Flux** or **Wall Heat Flux** in the result control, field calculation, or surface data options.

I also checked the SimScale documentation page on Result Control:

[https://www.simscale.com/docs/simulation-setup/result-control/](https://www.simscale.com/docs/simulation-setup/result-control/?utm_source=chatgpt.com)

As far as I understand, this page says that result control can be used to define additional simulation result outputs, and that surface data can calculate an average or integral of simulation results over a specified surface. However, I still cannot find where to enable or extract wall heat flux for my Convective Heat Transfer simulation.

Could you please clarify the following?

1. Is wall heat flux available for Convective Heat Transfer simulations?

2. If so, where exactly can I enable or extract it?

3. Should I use **Conjugate Heat Transfer** instead of **Convective Heat Transfer** to obtain wall heat flux between a solid acrylic plate and an air domain?

4. If direct wall heat flux output is not available in my setup, what is the recommended way to calculate heat flux from the simulation results?

My simulation consists of an air domain between two acrylic plates, with one side heated and natural convection occurring due to the temperature difference. I’ll post the URL and the image of my simulation below. Thank you.

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 ![image](https://www.simscale.com/forum/uploads/default/original/3X/1/0/103099e8a99e5d2540b61033a0530aed587f160d.jpeg)

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**Author:** ![BryanArsenio](https://www.simscale.com/forum/user_avatar/www.simscale.com/bryanarsenio/32/71634_2.png) [@BryanArsenio](https://www.simscale.com/forum/u/BryanArsenio)\
**Post date:** [June 19, 2026, 12:41pm UTC](https://www.simscale.com/forum/t/i-cant-find-convective-heat-flux-on-result-control-in-my-simulation/101120/3 "2026-06-19T12:41:10Z")

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Hi @shinynimij,

In the project link you shared you are using a fluid-only (air) Convective Heat Transfer analysis. In this setup, the acrylic plates are not modeled as actual solid bodies; they are only treated as boundary faces of the air domain.

Although you have assigned a No-Slip wall boundary condition, this only means that the fluid velocity at that wall is set to zero. It does not represent heat conduction through the acrylic plate itself.

Convective Wall Heat Flux should still be available as a result/control quantity for supported wall boundaries, usually under **Result Control \> Field Calculations**. However, if you want to evaluate heat transfer through the acrylic itself, or model the solid-fluid heat transfer more physically, then a **Conjugate Heat Transfer** setup would be the better workflow because it includes both the solid and fluid domains.

If you continue with the current setup, you can use the convective wall heat flux / Heat Transfer Coefficient post-processing workflow for estimating heat transfer and Nusselt number.

Thanks!  
Bryan