[fluent_noob]

Hello,


I am trying to simulate a system with different volumes and a heat source. The idea is that I initialize the system with the heater temperature set. After the thermal equilibrium is reached [say 1 sec] as in the attached figure. I want to introduce an energy source term (or atleast temperature term) for eg. 10 [W/m^3] * (1 + sin (10[Hz] * 2 * PI * 1 [rad / sec / Hz] * t)).
50_um_slit_laminar_total_temp_probe_1.JPG


I have following issues:
1. Do I have to use patching or I can just introduce an "energy source" in the cell zone condition and run the calculation?
2. If I have to use patching tool, there is no energy variable and even for temperture variable I can't provide a periodic function of the form 10 [K] * (1+sin(10[Hz] * 2 * PI * 1[rad / sec / Hz] * t)).
How can I patch/add the energy/temperature term for a particular cell zone after some time in transient simulation?

[MKuhn]

patch is only for initialization and timeless, therefor you can patch only pressure, temperature, velocity and so one. To introduce an "energy source" in the cell zone condition is the right way.

[fluent_noob]

Originally Posted by MKuhn

patch is only for initialization and timeless, therefor you can patch only pressure, temperature, velocity and so one. To introduce an "energy source" in the cell zone condition is the right way.

Thanks for the reply. I have 2 followup questions:
1. If I introduce the "energy source" term after 1 sec (~5000 iterations) and run the calculations, then for iterations beginning from 5001, the system solution will contain the effect due to the energy term as well?
2. If I introduce patch after 5000 iterations and run the calculation, 5001st calculation will have have effect due to the patched parameter as well. But this is without overall initialization. So what do you mean when you say "patch is ONLY for initialization ?

[MKuhn]

Originally Posted by fluent_noob

Thanks for the reply. I have 2 followup questions:
1. If I introduce the "energy source" term after 1 sec (~5000 iterations) and run the calculations, then for iterations beginning from 5001, the system solution will contain the effect due to the energy term as well?

Yes

Originally Posted by fluent_noob

2. If I introduce patch after 5000 iterations and run the calculation, 5001st calculation will have have effect due to the patched parameter as well. But this is without overall initialization. So what do you mean when you say "patch is ONLY for initialization ?

You cannot not patch a "energy source". For a steady state simulation the solution is idenpendent from what you patch. It will only help to improve some initialization values. For transient simulations with patch you can change conditions for a certain time. For example see my hints for the user in this thread.

[fluent_noob]

Thanks for that clear distinction and explanation. I am trying to compare both the methods mentioned above. Once pressure equivalent energy using energy source term and for other system patching the pressure directly. I use field function to provide the pressure of the form Pstatic + 50[mPa](1+sin(wt)).

Please refer the figure. Is the way of defining the pressure field function correct? The frequency that I specify in the field function is angular frequency or radial?

[MKuhn]

Sorry, you've lost me there. Maybe someone else can help here.