Hi Muhammad Basit Shafiq ,

It's simple; you can turn on the turbulence model and then active "laminar zone" for the shell zone in the cell zone conditions section.

What you are asking can lead to different approaches. Statistical methods based on Reynolds averaging requires to select explicitly the regions of the flows characterized by the regimes. Conversely, apporaches like LES or DNS will solve laminar, transitional and turbulent regimes but, depending on the Reynolds number, you need to have enough computational power.

You can do it by

1. Split the laminar and turbulent regions manually by using the BC panel.

2. Use a transition model

for more help, you can used this link where a similar question has been asked

https://www.researchgate.net/post/Is-it-feasible-in-fluent-to-simulate-domain-using-both-laminar-and-turbulence-models-in-the-related-region-in-the-domain-at-the-same-timeuse

Thanks Ashkan Ghafari

You mean to say that first I select say k-omega from the models and then in the cell zones condition just active "laminar" zone at the shell side?

Muhammad Basit Shafiq, that's right.

Yes, it is possible by two methods.Either divide the mesh regions by the two mesh models or build the UDF code and skip the turbulence viscosity in UDF for laminar.

Good luck!!