Weird problem in diesel spray in OpenFoam-1.6-ext

Slanth · July 3, 2016, 04:33

Hello, guys, I am using openFoam-ext-1.6 and simulation diesel spray. I am testing the original tutorial "aachenBomb". But i find a very weird problem. That is, a while after injection, diesel has evaporated to gas phase. I plot the contour of diesel mass fraction (gas phase) as below. (sorry I cannot attach the picture, don't know why)

As expected, the shape of contour should be round at any axial sections. After all, the injector is a single circular hole. Unfortunately, the the shape of contour is square. The gaseous diesel seems to diffuse faster in a direction than the other direction. I totally don't know why. Could somebody help me with this point? Thank you very much. Maybe it's because of mesh? DieselFoam cannot use totally orthogonal mesh?

Slanth · July 3, 2016, 04:40

Okay, the pictures have been attached. Could anyone help me out of this? Thank you very much.

Slanth · July 4, 2016, 06:13

If this is because of mesh problem, a radiation grid surrounding the nozzle hole center is better. However, are there any solutions to improve the diffusion of gaseous vapor rather than replacing the mesh? After all, for engine diesel spray simulations, it's so difficult to make a radiation type grid. If it's possible to improve the solver or class of dieselSpray?

I am really urgent to need help, Thank you very much.

Slanth · July 10, 2016, 19:42

Hello, guys, I am thinking if some kind of filtering method could solve this nonuniform diffusion problem, such as gauss filtering? It;s really appreciated that anybody could give a hint about this.

July 3, 2016, 04:33	Weird problem in diesel spray in OpenFoam-1.6-ext	#1
Slanth New Member Join Date: Mar 2013 Posts: 24 Rep Power: 13	Hello, guys, I am using openFoam-ext-1.6 and simulation diesel spray. I am testing the original tutorial "aachenBomb". But i find a very weird problem. That is, a while after injection, diesel has evaporated to gas phase. I plot the contour of diesel mass fraction (gas phase) as below. (sorry I cannot attach the picture, don't know why) As expected, the shape of contour should be round at any axial sections. After all, the injector is a single circular hole. Unfortunately, the the shape of contour is square. The gaseous diesel seems to diffuse faster in a direction than the other direction. I totally don't know why. Could somebody help me with this point? Thank you very much. Maybe it's because of mesh? DieselFoam cannot use totally orthogonal mesh?

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July 4, 2016, 06:13		#3
Slanth New Member Join Date: Mar 2013 Posts: 24 Rep Power: 13	If this is because of mesh problem, a radiation grid surrounding the nozzle hole center is better. However, are there any solutions to improve the diffusion of gaseous vapor rather than replacing the mesh? After all, for engine diesel spray simulations, it's so difficult to make a radiation type grid. If it's possible to improve the solver or class of dieselSpray? I am really urgent to need help, Thank you very much.

July 10, 2016, 19:42		#4
Slanth New Member Join Date: Mar 2013 Posts: 24 Rep Power: 13	Hello, guys, I am thinking if some kind of filtering method could solve this nonuniform diffusion problem, such as gauss filtering? It;s really appreciated that anybody could give a hint about this.