How can I extract the Nusselt number over time in Ansys for a cavity model?

In summary, the conversation discusses the process of exporting the Nusselt number over time in order to analyze the variation of natural convection heat transfer inside a heat exchanger modeled in Ansys. The participants suggest using the Reports function to extract the Nusselt number for a specific time, but the original poster is looking for a way to export the Nusselt number for every time step or a specific time step. The possibility of using transient solving and loading time sections of the result is also mentioned.
  • #1
alikarimi
3
0
Hi everybody

I built a cavity model in Ansys in order to modelling natural convection heat transfer inside a heat exchanger. But I do not know how to export Nusselt number over time. I need to see how it varies while time passing. Please help me. I know that from Reports part of software I can extract Nusselt number though it is just for one specific time. I need to show its variation versus time.
 
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  • #2
Can you export h, the convection coefficient, as a function of time? If so then you have your Nusselt number because presumably k and L are fixed.
 
  • #3
Thank you boneh3ad.

At first I want to check my procedure of exporting nusselt number whether it is true or false:

Reports>Report type>Area-Weighted Average
Field Variable>Wall Fluxes>Surface Nusselt Number

Every time I want to check the nusselt number, I should do the above procedure.

For convection coefficient (h) is the same. I can not draw it over time. I think there should be some method to export Nu or h versus time. Please help me to find it.
 
  • #4
do you using the transient solve for the this problem, and how much is the total time duration and how much is time step?

For transient solving, you can load the time section(certain times of time step) result and plot the result such as H or Nusselt
 
  • #5
Thank you chaos_zzy.

What do you mean by "load the time section(certain times of time step) result"?

I want to see the variation of Nusselt number with time. So I should get the nusselt number for every time step (or any other specific time step which I can adjust).

If you have any idea, please send me.
 

Related to How can I extract the Nusselt number over time in Ansys for a cavity model?

1. What is the Nusselt number over time?

The Nusselt number over time is a dimensionless quantity used in fluid mechanics to measure the ratio of convective to conductive heat transfer. It is defined as the ratio of the convective heat transfer coefficient to the conductive heat transfer coefficient.

2. How is the Nusselt number over time calculated?

The Nusselt number over time can be calculated using the following equation: Nu = (hL) / k, where h is the convective heat transfer coefficient, L is the characteristic length, and k is the thermal conductivity of the fluid.

3. What does a high Nusselt number over time indicate?

A high Nusselt number over time indicates a high rate of convective heat transfer, meaning that the fluid is able to transfer heat more efficiently than through conduction alone.

4. How does the Nusselt number over time change with flow rate?

The Nusselt number over time is directly proportional to the flow rate of the fluid. This means that as the flow rate increases, the Nusselt number also increases, indicating a higher rate of convective heat transfer.

5. What factors affect the Nusselt number over time?

The Nusselt number over time can be affected by various factors, such as fluid properties (viscosity, density, thermal conductivity), flow rate, surface roughness, and geometry of the system. Changes in any of these factors can alter the convective heat transfer and thus, the Nusselt number over time.

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