topic CFD results giving weird values in CFD Forum

CFD results giving weird values

Arun.Cherian — Fri, 23 Dec 2022 12:05:09 GMT

Hi I am getting weird results in bulk results like - value for temperature and flow and even though the color plot is within acceptable temperature range. I have attached my file in below link for review.

https://wetransfer.com/downloads/e5ef26ecb4d1fde5ee8e6fe3d967e0a320221223115802/3ccb3aa597108da6fc0e7a2ed056e10f20221223115823/66a4ee

Re: CFD results giving weird values

Arun.Cherian — Tue, 03 Jan 2023 09:23:19 GMT

Hello is anyone evaluating this case? Did get any response yet

Re: CFD results giving weird values

marwan_azzam — Tue, 03 Jan 2023 12:58:28 GMT

Hello Arun,

Every one was on holiday the past 1-2 weeks.

The link to the model expired. Please provide a new link.

cheers,

Marwan

Re: CFD results giving weird values

Arun.Cherian — Tue, 03 Jan 2023 13:21:50 GMT

Hi Marvan,

I did many options below is one file where I had similar issues

The file I shared above with issues on -ve temperature and flow

https://keoic-my.sharepoint.com/:u:/p/arun_cherian/EdSQbtt60llHqnuBJRqKlv8BPPADZMf-P9cIQCFIH9gJHg?e=kqDNeo

Side closed with floor diffusers where the flow is not consistent at different level

https://wetransfer.com/downloads/f43425abfec69eac117f2c6bfd35d76820230103131336/40f96914ebc2b3567ab9d72029e7a6b020230103131354/e10be7

Re: CFD results giving weird values

marwan_azzam — Tue, 03 Jan 2023 19:03:27 GMT

Hello,

The model where the flow is not consistent (the cfz file without results) does not make sense since you have 100 inlets but no outlets. Please correct me if I'm wrong.

The other model with the negative temperature. I assume that surface 47 where you have P=0 is an outlet. If so, you need to delete the temperature BC on that surface since it's an outlet and the program will calculate the outlet air temperature.

Marwan

Re: CFD results giving weird values

Arun.Cherian — Wed, 04 Jan 2023 07:34:40 GMT

Hi Marwan,

Note that this is a case of solar heating with wind effect and cooling via diffusers.

In both the cases the tent is within an external fluid domain with P outlet and conditions as per below tutorial

Assign Temperature Boundary Condition to Environment | CFD 2019 | Autodesk Knowledge Network

The 100 inlet diffusers are within the tent with, and the opening is on the roof as u see in the model and naturally due the flow the air will move out and pressure is applied on the external boundary condition typical to any software even.

For the second case the pressure and temperature at outlet of external fluid is not the issue it is some issue with the software I feel it shouldn't give these kinds of results I tried different open still same issue.

The main issue what I see is the at different levels within the tent along Z direction for 100 DF case the mass is not conserved and is fluctuating, and error is greater than 10% which is not acceptable. Please check how this issue can be resolved I tried even refining the mesh still I had the same issue.

Please check this.

Re: CFD results giving weird values

Arun.Cherian — Wed, 11 Jan 2023 06:34:54 GMT

Hi Marwan,

I am waiting for your reply. We have client presentation, and could you let know what the issue is as the results is are not reliable.