The experiment was conducted with a cavity of internal dimensions of H=2.18m high, D= 0.0762m wide and 0.52rn deep. One vertical wall was at 15 degrees C and the other at 35 degrees C for Ra= 8.5 ×105, and 15 degrees C and 55 degrees C for Ra =15.3 ×105. Results include mean and turbulent (rms) vertical velocity and temperature.
On the other hand, the incompressible Navier-Stokes equations using the Boussinesq approximation of density have been solved by a pseudo-spectral/finite difference DNS code for the flow between two infinite vertical walls and for Ra= 1.0 ×105 & Ra= 5.4 ×105. All first and second moments, and their budgets, are provided. Mean and rms fluctuating values normalized by the buoyancy velocity agree well with the experiment. A still open question is the slight disagreement concerning the friction velocity with an other DNS performed by Niewstadt and Versteegh.
Directions 1,2,3 correspond to x,y,z respectively, where x is the stream wise ascending co-ordinate, y is the spanwise co-ordinate, z is the wall normal co-ordinate (z=0 for the hot wall and z=1 for the cold one).
|
Rayleigh number |
| D | gap width |
| DT | temperature difference between walls |
| Pr=v/k | Prandtl number |
| g | gravity acceleration |
| b | thermal expansion |
| v | molecular viscosity |
| k | thermal diffusivity |
|
friction velocity |
|
gradients taken at wall |
|
buoyancy velocity |