HTC Map Utility

kri321shna · December 27, 2016, 12:20

Hi All,

Happy Christmas

How to create FEA_surface.dat for htc_map utility.

Thanks

Best Regards,
Krishna

kri321shna · December 28, 2016, 15:45

Hi all,

we can consider same converge surface.dat file as FEA_surface.dat

dprobst · December 30, 2016, 12:11

We have an example of htc_mapping on the downloads section of our website that can guide you through the process of mapping and describes the FEA surface. The FEA_surface.dat is similar to the surface.dat but typically has more resolution on the liner and valve stems and does not include inflow or outflows.

MFGT · January 21, 2017, 10:14

Regarding the HTC. I have ran a simulation with spatial temperature distribution and got some weird average HTCs for Liner and Head boundary?

I guess it has to do with the cells changing, or spray parcels hitting the wall. So at times (around -50 to -20CA) they are changing like this from timestep to timestep:

...
39187,575
-2336,3172
-95579,236
-127767,93
16728,665
11152,817
...

I have attached a textfile thats shows the data for Liner and Piston.

dprobst · February 3, 2017, 17:35

That looks odd. Can you send us the case to look at?
The htc in transfer.out should not be negative by definition.
Wall films will create local spots with very high htc typically

MFGT · February 4, 2017, 13:15

Its not in the transfer.out file.
I am refering to the wall boundary output, which includes averaged HTCs for each boundary.

dprobst · February 10, 2017, 10:39

The htc in bound wall can be negative if the film temp is below the wall temp, when the gas temp is higher. The htc is always using the near wall gas temp as the reference.
If the average htc is changing like your file is showing, it probably indicates that a cold film is forming on the wall as droplets impinge.

MFGT · February 11, 2017, 05:43

Yeah, i thought it had something to do with the wall film. However, if i output my bound_htc in Ensight i do not see these spots. Here the distribution looks quite normal withough the high up/down peaks.

dprobst · February 13, 2017, 12:14

The bound_htc in post does not include the film effect as it outputs just the convective term.
When a film exists, an energy balance on the film includes the convective side and the conduction side to the wall.
Take a look at wall film in post and I expect you will see film where you have spots.

December 27, 2016, 12:20	HTC Map Utility	#1
kri321shna Member Krishna Join Date: Apr 2012 Posts: 54 Rep Power: 14	Hi All, Happy Christmas How to create FEA_surface.dat for htc_map utility. Thanks Best Regards, Krishna

December 30, 2016, 12:11		#3
dprobst Member Dan Probst Join Date: Jan 2016 Location: Convergent Science, Madison WI Posts: 38 Rep Power: 10	We have an example of htc_mapping on the downloads section of our website that can guide you through the process of mapping and describes the FEA surface. The FEA_surface.dat is similar to the surface.dat but typically has more resolution on the liner and valve stems and does not include inflow or outflows. __________________ Dan Probst Principal Engineer CONVERGECFD

February 3, 2017, 17:35		#5
dprobst Member Dan Probst Join Date: Jan 2016 Location: Convergent Science, Madison WI Posts: 38 Rep Power: 10	That looks odd. Can you send us the case to look at? The htc in transfer.out should not be negative by definition. Wall films will create local spots with very high htc typically __________________ Dan Probst Principal Engineer CONVERGECFD

February 10, 2017, 10:39		#7
dprobst Member Dan Probst Join Date: Jan 2016 Location: Convergent Science, Madison WI Posts: 38 Rep Power: 10	The htc in bound wall can be negative if the film temp is below the wall temp, when the gas temp is higher. The htc is always using the near wall gas temp as the reference. If the average htc is changing like your file is showing, it probably indicates that a cold film is forming on the wall as droplets impinge. __________________ Dan Probst Principal Engineer CONVERGECFD

February 13, 2017, 12:14		#9
dprobst Member Dan Probst Join Date: Jan 2016 Location: Convergent Science, Madison WI Posts: 38 Rep Power: 10	The bound_htc in post does not include the film effect as it outputs just the convective term. When a film exists, an energy balance on the film includes the convective side and the conduction side to the wall. Take a look at wall film in post and I expect you will see film where you have spots. __________________ Dan Probst Principal Engineer CONVERGECFD

December 28, 2016, 15:45		#2
kri321shna Member Krishna Join Date: Apr 2012 Posts: 54 Rep Power: 14	Hi all, we can consider same converge surface.dat file as FEA_surface.dat

February 4, 2017, 13:15		#6
MFGT Senior Member Tobias Join Date: May 2016 Location: Germany Posts: 265 Rep Power: 10	Its not in the transfer.out file. I am refering to the wall boundary output, which includes averaged HTCs for each boundary.

February 11, 2017, 05:43		#8
MFGT Senior Member Tobias Join Date: May 2016 Location: Germany Posts: 265 Rep Power: 10	Yeah, i thought it had something to do with the wall film. However, if i output my bound_htc in Ensight i do not see these spots. Here the distribution looks quite normal withough the high up/down peaks.

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