How Detonation wave behaves in microgravity?

huzaim · September 15, 2025, 02:53

I want to simulate the combustion on Ansys at near 0g microgravity. I am unable to sort out that I should start from where. Main objective is to study the detonatoin wave behaviour in space/microgravity. Can anyone help me in detail. Very less online resources are availbe for this. I request you to guide me so I can study in depth.

FMDenaro · September 15, 2025, 04:27

Quote:

Originally Posted by huzaim

I want to simulate the combustion on Ansys at near 0g microgravity. I am unable to sort out that I should start from where. Main objective is to study the detonatoin wave behaviour in space/microgravity. Can anyone help me in detail. Very less online resources are availbe for this. I request you to guide me so I can study in depth.

In absence of atmosphere (no combustion) is impossible, do you imagine a controlled environment like in the ISS?

huzaim · September 15, 2025, 04:55

Yes dear sir , you are right. I meant to say that in controlled enviornment with fuel and oxidizer feed system. I am confused that where to start. I know th effect of microgravity on flame but don't really understand how to simulate it in ANSYS.. only limiting g vector will serve this purpose or not?

FMDenaro · September 15, 2025, 05:04

Quote:

Originally Posted by huzaim

Yes dear sir , you are right. I meant to say that in controlled enviornment with fuel and oxidizer feed system. I am confused that where to start. I know th effect of microgravity on flame but don't really understand how to simulate it in ANSYS.. only limiting g vector will serve this purpose or not?

For sure you have to set g tending to zero.
In general microgravity fluid dynamics, other effects appear relevant due to Marangoni effect. In your case I don’t think they would be relevant.

Gerry Kan · September 16, 2025, 07:50

You might also want to look at the early works pertaining to (spark) ignition - e.g., in the 1980s, and some of the works on premixed ignition modelling. They focused at the time before gravitational effects become significant. This should give you an idea how to proceed.

Fillipo is right, depending on the prevailing turbulence, you should expect the flame front to form cells due to a combination of temperature and concentration inhomogeneities resulting from ambient interaction. I don't know if these are your points of interest.

Another thing to consider it the characterization of turbulence in ANSYS. That is, whether you are expecting an initially quiescent condition. All I can say is, if this is the case, you cannot use a RANS approach because this will grossly overpredict the flame speed, and I am speaking from experience. You will need to use LES so more correctly capture the transition to turbulence.

You will need to think through how you are setting up your model, i.e., under what conditions you will be conducting these runs. Especially due to turbulence representation I have mentioned before, it is not as straightforward as it seems.

Hope it helps, Gerry.

huzaim · September 17, 2025, 04:38

you are right sir. I am not very much expert in CFD. I am assigned to investigate the effect microgravity on rotating detonation engine. I am struggling to find good literature on it. Yeah,you're feedback somehow showed me path. I am mech undergrad student. if you want to add more pls. It will really help me. I just need right direction.

bigfootedrockmidget · September 17, 2025, 08:38

A recent paper with some computational details can be found here:
Peng and Deiterding (2025)

https://www.sciencedirect.com/scienc...66352X24000712

They do not use a gravity source term, because buoyancy is often not important in combustion (exceptions are e.g. pool fires, or candle flames where the air draft is important).

In any case, from this paper it looks like you can get pretty decent results with limited computing time, less than 1,000 cpu-hrs for a computation on a 1M cell mesh, and it's only second order.

FMDenaro · September 17, 2025, 09:15

Quote:

Originally Posted by huzaim

you are right sir. I am not very much expert in CFD. I am assigned to investigate the effect microgravity on rotating detonation engine. I am struggling to find good literature on it. Yeah,you're feedback somehow showed me path. I am mech undergrad student. if you want to add more pls. It will really help me. I just need right direction.

The real problem is that an undergaduated student should not have been assigned such a problem only because there is Ansys…

calim_cfd · September 17, 2025, 10:24

Quote:

Originally Posted by FMDenaro

The real problem is that an undergaduated student should not have been assigned such a problem only because there is Ansys…

True story, unfortunately, it is not the only one. This is my main complaint about robust (in the sense of "running" things) commercial solvers, they make it look like it is mostly a pre-proc interface issue by hiding the elephants which are the solvers and couplers.

Nonetheless, this artificial aid has led many to the CAE area. Once here, some fell in love and face the endless updates whereas others leave to live a more "normal life"

Gerry Kan · September 18, 2025, 05:20

Quote:

Originally Posted by huzaim

you are right sir. I am not very much expert in CFD. I am assigned to investigate the effect microgravity on rotating detonation engine. I am struggling to find good literature on it. Yeah,you're feedback somehow showed me path. I am mech undergrad student. if you want to add more pls. It will really help me. I just need right direction.

When I saw your original message I had a very different understanding on what you are trying to do. Given this topic, you should understand that this is a very complex problem involving chemical kinetics, thermoacoustics and shock wave propagation (from detonation). I don't think for what you want to do this is appropriate technically at an undergraduate level.

Are you sure you are not asked to simply write a 10-page (literature) review on this, whereupon a fully working numerical model is only "nice-to-have"?

huzaim · September 19, 2025, 06:25

You’re absolutely right, sir. I have to work on this myself, so I’m going through all the available literature and research papers. Due to the absence of buoyancy and gravity, it’s still uncertain whether a detonation wave will even form. And even if it does, there’s no guarantee it will remain sustained. There are many complex factors at play simultaneously. But with proper guidance from you and other experienced people, I’m hopeful that we’ll be able to achieve meaningful results.

September 15, 2025, 02:53	How Detonation wave behaves in microgravity?	#1
huzaim New Member hm Join Date: Jun 2025 Posts: 4 Rep Power: 2	I want to simulate the combustion on Ansys at near 0g microgravity. I am unable to sort out that I should start from where. Main objective is to study the detonatoin wave behaviour in space/microgravity. Can anyone help me in detail. Very less online resources are availbe for this. I request you to guide me so I can study in depth.

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September 15, 2025, 04:55		#3
huzaim New Member hm Join Date: Jun 2025 Posts: 4 Rep Power: 2	Yes dear sir , you are right. I meant to say that in controlled enviornment with fuel and oxidizer feed system. I am confused that where to start. I know th effect of microgravity on flame but don't really understand how to simulate it in ANSYS.. only limiting g vector will serve this purpose or not?

September 16, 2025, 07:50		#5
Gerry Kan Senior Member Gerry Kan Join Date: May 2016 Posts: 382 Rep Power: 12	You might also want to look at the early works pertaining to (spark) ignition - e.g., in the 1980s, and some of the works on premixed ignition modelling. They focused at the time before gravitational effects become significant. This should give you an idea how to proceed. Fillipo is right, depending on the prevailing turbulence, you should expect the flame front to form cells due to a combination of temperature and concentration inhomogeneities resulting from ambient interaction. I don't know if these are your points of interest. Another thing to consider it the characterization of turbulence in ANSYS. That is, whether you are expecting an initially quiescent condition. All I can say is, if this is the case, you cannot use a RANS approach because this will grossly overpredict the flame speed, and I am speaking from experience. You will need to use LES so more correctly capture the transition to turbulence. You will need to think through how you are setting up your model, i.e., under what conditions you will be conducting these runs. Especially due to turbulence representation I have mentioned before, it is not as straightforward as it seems. Hope it helps, Gerry.

September 17, 2025, 04:38		#6
huzaim New Member hm Join Date: Jun 2025 Posts: 4 Rep Power: 2	you are right sir. I am not very much expert in CFD. I am assigned to investigate the effect microgravity on rotating detonation engine. I am struggling to find good literature on it. Yeah,you're feedback somehow showed me path. I am mech undergrad student. if you want to add more pls. It will really help me. I just need right direction.

September 17, 2025, 08:38		#7
bigfootedrockmidget Senior Member bigfoot Join Date: Dec 2011 Location: Netherlands Posts: 817 Rep Power: 22	A recent paper with some computational details can be found here: Peng and Deiterding (2025) https://www.sciencedirect.com/scienc...66352X24000712 They do not use a gravity source term, because buoyancy is often not important in combustion (exceptions are e.g. pool fires, or candle flames where the air draft is important). In any case, from this paper it looks like you can get pretty decent results with limited computing time, less than 1,000 cpu-hrs for a computation on a 1M cell mesh, and it's only second order.

September 19, 2025, 06:25		#11
huzaim New Member hm Join Date: Jun 2025 Posts: 4 Rep Power: 2	You’re absolutely right, sir. I have to work on this myself, so I’m going through all the available literature and research papers. Due to the absence of buoyancy and gravity, it’s still uncertain whether a detonation wave will even form. And even if it does, there’s no guarantee it will remain sustained. There are many complex factors at play simultaneously. But with proper guidance from you and other experienced people, I’m hopeful that we’ll be able to achieve meaningful results.