Wall Temperature Distribution

[appheadspace]

Hi, Please help me in implementing temperature distribution of wall in 2D cavity. Kindly help, I'm new to FDS and after seeing FDS user guide, I've tried 3 approaches and all are not working !

I've tried this:

APPROACH-1:::

&SURF ID='bottom_wall', RAMP_T='bottom_temp_ramp' /
&RAMP ID='bottom_temp_ramp', T=0.0, F=50.0 /
&RAMP ID='bottom_temp_ramp', T=0.00067, F=46.91 /
&RAMP ID='bottom_temp_ramp', T=0.0133, F=45.15 /

Approach-2:::

&OBST XB=0,0.750,-0.00005,0.00005,0,0 , SURF_ID='bottom_wall' /
&SURF ID = 'bottom_wall', COLOR = 'GRAY', RAMP_T = Bottom_Temp_Ramp, TMP_FRONT = 30/

&RAMP ID='Bottom_Temp_Ramp', T=0, F=1.6667
&RAMP ID='Bottom_Temp_Ramp', T=0.00015, F=1.5987
&RAMP ID='Bottom_Temp_Ramp', T=0.005025, F=1.5777

Approach -3:::

&OBST XB=0,0.750,-0.00005,0.00005,0,0 , SURF_ID='bottom_wall' /
&SURF ID = 'bottom_wall', COLOR = 'GRAY'/

&OBST XB =0,0,-0.00005,0.00005,0,0 ,SURF_ID='BW1'/
&SURF ID = 'BW1',TMP_FRONT =50/

&OBST XB =0.00015,0.00015,-0.00005,0.00005,0,0 ,SURF_ID='BW2'/
&SURF ID = 'BW2',TMP_FRONT =47.96/

&OBST XB =0.005025,0.005025,-0.00005,0.00005,0,0 ,SURF_ID='BW3'/
&SURF ID = 'BW3',TMP_FRONT =47.33/

bottom wall temperatures are showing 0 (for approach-1) and 30(for approach 2,3) at all locations.
(PS: In my case INIT temp and TMPA , both are 30)

Kindly guide me. I'm new to FDS.

[mcgratta]

TMP(T) = TMPA + F*(TMP_FRONT-TMPA)

[appheadspace]

Thanks @mcgratta for your reply!. I tried the below approach by changing TMP_FRONT but the temp is 13.369912 for all locations in bottom wall. Please check and Kindly guide me.

&MISC STRATIFICATION=F, SIMULATION_MODE='LES', TMPA = 30./

&SURF ID = 'bottom_wall', COLOR = 'GRAY', RAMP_T = Bottom_Temp_Ramp, TMP_FRONT = 20/

&RAMP ID='Bottom_Temp_Ramp', T=0, F=-2/
&RAMP ID='Bottom_Temp_Ramp', T=0.00015, F=-1.674/
&RAMP ID='Bottom_Temp_Ramp', T=0.005025, F=-1.615/
&RAMP ID='Bottom_Temp_Ramp', T=0.009975, F=-1.545/
&RAMP ID='Bottom_Temp_Ramp', T=0.020025, F=-1.456/
&RAMP ID='Bottom_Temp_Ramp', T=0.039975, F=-1.093/
&RAMP ID='Bottom_Temp_Ramp', T=0.075, F=-0.643/
&RAMP ID='Bottom_Temp_Ramp', T=0.15, F=-0.105/
&RAMP ID='Bottom_Temp_Ramp', T=0.225, F=0.192/
&RAMP ID='Bottom_Temp_Ramp', T=0.3, F=0.416/
&RAMP ID='Bottom_Temp_Ramp', T=0.375, F=0.599/
&RAMP ID='Bottom_Temp_Ramp', T=0.45, F=0.754/
&RAMP ID='Bottom_Temp_Ramp', T=0.525, F=0.911/
&RAMP ID='Bottom_Temp_Ramp', T=0.6, F=1.184/
&RAMP ID='Bottom_Temp_Ramp', T=0.675, F=1.404/
&RAMP ID='Bottom_Temp_Ramp', T=0.729975, F=1.822/
&RAMP ID='Bottom_Temp_Ramp', T=0.740025, F=1.87/
&RAMP ID='Bottom_Temp_Ramp', T=0.7485, F=1.926/
&RAMP ID='Bottom_Temp_Ramp', T=0.75, F=2/

[mcgratta]

Post a very simple input file.

[drjfloyd]

What is the area of this OBST?

&OBST XB =0,0,-0.00005,0.00005,0,0 ,SURF_ID='BW1'/

[appheadspace]

.

[drjfloyd]

You did not answer my question.

The User's Guide explains that the XB for an OBST will snap to the grid. Then every wall cell on that snapped OBST will get the SURF_ID.

What is the area of the OBST you defined? Based on your grid and that area, how many wall cells will be assigned your SURF_ID?

[appheadspace]

XB =0,0,-0.00005,0.00005,0,0 is a line of length (0.00005x2 =) 0.0001 m at x=0 and z = 0. Since line is 1D, so no area.

[drjfloyd]

Zero area means zero wall cells are being assigned your SURF_ID.

[appheadspace]

Oh! Thank you so much for explaining this. I will change my input file accordingly and try to get the result. Will come back here again if anything doesn't go right. Once again, thank you!