## 3D Design

#### Geometry for external environment

• rrdbes
Subscriber

HI! How can i possible represent the external environment around a building so that i can also see the wind distribution around the structure like in the attached image. Im working on a 2D analysis and i want to both see the wind inside and outside the structure. Thank You!

• peteroznewman
Subscriber

Drag out a Fluent system. On the Geometry cell, set the property to 2D before you start DM or SC. Draw a big rectangle to be the air. Leave more air downstream than upstream around the structure. Cut pieces out to be the roof or walls. Named selections for Inlet, Outlet, Wall-roof, Wall-ground and Symmetry on the top help to define the Fluent conditions.

Below is the velocity plot for a 5 m/s uniform wind velocity at the left edge.

I am learning CFD, so if there are some improvements or corrections to this model, I will be glad to hear about them.
Perhaps moving the left, top and right boundaries further away would be better. Attached is an ANSYS 18.2 archive.

• rrdbes
Subscriber

I'm thinking a method where in the walls and roof are not to be subtracted from the surface. Will be using the walls in radiation model. Is it possible? Thanks!

• peteroznewman
Subscriber

Then you have multiple surfaces. One surface is the air domain and has a cutout for each solid domain. Each solid domain is its own surface body. All the surface bodies are put into a single part so that the mesher knows to connect the nodes at the interface.

• Raef.Kobeissi
Subscriber

Do you mean, you want the walls to be meshed and represented as solid material? if that's the case you need to make sure that the solid wall interface is coupled with the fluid wall and that you have 2 zones  (1 for fluid and another for solid).

• peteroznewman
Subscriber

@rrdbes, I just found your very first post with a more complete description of the house and the sun.

When you define the roof material, you will need to specify the thermal conductivity, so heat can conduct from the outside to the inside. You also have to specify the emissivity of the surfaces. The absorptivity of the roof is equal to its emissivity when in thermal equilibrium according to Kirchoff's law of thermal radiation.