'Verification of a CFD model for indoor airflow and heat transfer' simulation project by vgon_alves


#1

I created a new simulation project called 'Verification of a CFD model for indoor airflow and heat transfer':

The purpose of this project is to validate the accuracy of the solver for indoor convective heat transfer. The velocity and temperature contours are to be compared with the proposed results.


More of my public projects can be found here.


#2

Description


Overview

In ventilated interior enviroments of buildings, the determination of air-flow velocities, temperatures and concentrations of polluants is required to evalute comfort conditions [1]. The experimental data of Loomans [2] as well as the CFD profiles of Stamou were used here for verification of the model.

The purpose of this project is to validate the accuracy of the SimScale solver for indoor convective heat transfer.The airflow pattern (velocity) and temperature results from CFD will be compared with the proposed results.

Geometry

Geometry was created by using Ansys SpaceClaim v17.2. According to the source, the air inlet is located below the table, and the outlet is on top of the room, like a exhaust fan. While this, there are some heat exchangers with the room as computers, light bulbs, iluminations and a person.


Fig 1. Geometry’s general vision

sidebody
Fig 2. Dimensions of the body


Fig 3. Dimensions of the distances between the heat sources and the inlet and outlet

front
Fig 4. Dimensions of the geometry in a front view


Fig 5. Dimensions of the geometry in a top view

Mesh

The mesh used in the simulations of this case were created in SimScale using Hex-Dominant Parametric with surface refinements at walls, inlet, outlet and the body. Thus, the mesh was finished with 1321242 nodes, 3390477 2D elements and 1037555 3D elements.


Fig 6. Visualization of the mesh with a cross section of the mesh


Fig 7. Emphasis at the body mesh and the perpendicular outlet surface.

Simulation Setup

Using Convective Heat Tranfer as analysis type:

Air was considered in all the domain with default values which there are in the SimScale library At the initial conditions the Modifield Pressure remained default like 101325[Pa]; Velocity was considered 0.01[m/s] in the y direction; Temperature = 293[K] ; Dynamic viscosity value = 0[kg/(s m)]; Turbulent kinetic energy value = 0.00375[m²/s²]; Specific turbulence dissipation rate = 3.375 [1/s]; Turbulent thermal diffusivity = 0[kg/(s m)].

The accuracy of the results is highly dependent of the flow profiles of mean air speed and temperatures that are applied in the heat sources. These profiles should be fully developed and representative at the domain, according to the source.
OBS1:Therefore, as “Q” reads "Heat"

image

Fig 8. Boundary conditions

Results and discussion

It is observed that wall temperature on the Floor (solid_0_solid_0_face_84) is maximum while on the Southern wall (solid_0_solid_0_face_86) is the minimum temperature. Using k-omega SST the results characteristics of the flow are demonstrates at Fig. 11 and Fig. 12.

Max. Temperature


Fig 9. Maximum Temperature at the wall

Min. Temperature


Fig 10. Minimum Temperature at the wall

Temperature distribution


Fig 11. Temperature contours and velocity vectors at the central xy plane

Temperature distribution


Fig 12. Streamlines (U) with PC1, PC2 and ilumination’s temperature at the central xy plane

Comparison with experimental data in the source:
About temperature, the results are passing the source something like 3ºC. The velocity vectors are more vertical than the source wich shows more diagonal vectors in the region between the computer and the body. Others turbulence models were used (like k-epsilon and laminar) to comparison, but they don’t was able to show the diagonals vectors neither reduce the 3ºC divergence as well.

Sources

  • [1] A. Stamou, I. Katsiris, Verification of a CFD model for indoor airflow and heat transfer, Building and Environment, Volume 41, Issue 9, 2006, Pages 1171-1181, ISSN 0360-1323, http://dx.doi.org/10.1016/j.buildenv.2005.06.029

  • [2] Loomans M. The measurement and simulation of indoor air flow. Phd. thesis. The Netherlands: University of Eindhoven; 1998.

  • [3] Zhang W, Chen Q. Large eddy simulation of indoor airflow with a filtred dynamic sub-grid scale model. International Journal of Heat and Mass Transfer 2000;43(17):3219-31.


[FINISHED] Verification of a CFD model for indoor airflow and heat transfer
#3

Congrats! Excellent project!