| 초록 |
Buoyancy driven secondary flow in a forced laminar flow through a bottom heated horizontal channel can cause significant heat transfer enhancement. In the present study the finite element method was used to simulate this mixed convection in a horizontal fluid layer. In order to observe the behavior of vortex rolls, the three characteristic streamwise distances ( xc, xd, xu) and the growth rates ( r0, r1,TE,r1,KE) based on the numerical data are suggested newly. We suggest that the critical condition of the onset of intrinsic instability would be r0=r1,TE at x=xc . Also, we suggest that the secondary flow would be detected with r1,KE= maximum at x=xd. Finally, we suggest that the significant heat transfer enhancement starts from x=xu. In the present study the above characteristic distances agree well with available experimental data. |
