In the 6:00, for the scattering effect calculation ( the second term on the right), it should be sigma_s/4pi not sigma/4pi. Thank you for your great video.
Endorsed your point view " it is challenging and really tough to put it together". Though I am an advanced level user of discrete Ordinate (DO) model and published impact factor research articles using DO model. But your explanation is simple, structured and easily comprehensible. My salutation to you. Keep it up.
Thank you very much, sir. I m definitely buying you a couple of pints after submitting my master thesis.Hats off to your invaluable work in youtube. Greetings from Spain.
Such a beautiful explanation of such complicated model. Many thanks and Best Wishes. Hope u will soon create a video on P1 model and the modeling of absorption coeff. and scattering function.
Amazing presentation! In just 1 hour (I listened back and forth), my level of understanding of not only DOM, but also RTE has been raised significantly! Thank you!
8:40 Delighted to hear your explanation. It seems clear that the RTE doesn't explicitly describe radiation heating/cooling, which should affect the temperature field. Of course, one can empirically use a "resultant temperature" distribution in space.
Very nice video; thank you! However, the radiation does not only interact with the fluid at the wall. Regions of gas that emit net radiation will get cooler, and those that have net absorption will get hotter. This is captured in the energy equation, which you did not show in this video. The energy equation is coupled volumetrically (not just at the boundaries) to the RTE though a new term in the energy equation, the divergence of the radiative flux. That is calculated by a radiative energy balance on a control volume using each of the I's calculated.
Thank you Aidan! This is extremely useful as I am doing a radiation simulation. I have become a patron as I think your textbook will be very helpful while learning CFD. Just go on and upload more video and I will support you as always.
I just don't know how to congratulate u or say thank u to u..which I generally i don't do..i really fund this lecture very much informative and interesting.. Thanks a lot and really really appreciate your efforts..
great content as always! have you considered doing any video on the energy cascade for turbulence and subsequent FFT analysis? always struggled getting this set up correctly
Hi, very interesting theory about the model but I have a question. Where can I get values of properties material such as concrete or sidewalk for DO model ( scattering, absorption and refractive index)? Could you provide them if you have it please? Regards
30:15 For gases, the refractive index can be approximated as unity, but the emission coefficent, or emissivity, may not be equal to absorption coefficent.
Very nice talk indeed. Why is the absorption within the media not taken into account when looking at the sources/interaction with the temperature, e.g. As an additional volumetric source? Since the intensity is changing doesnt that the mean the energy needs to go somewhere?
I agree, The medium should heat up since it is participating in the radiation. How will that happen if the radiation only interacts at the walls? The absorbed radiation and the emitted black body radiation at a point should participate in the energy balance at that point.
@@moma8956 You are correct. The radiation does not only interact at the wall. Regions of gas that emit net radiation will get cooler, and those that have net absorption will get hotter. This is captured in the energy equation, which he did not show. That is absolutely coupled volumetrically to the RTE though a new term in the energy equation, the divergence of the radiative flux.
In the fluid region where gas particles exist, is the radiation from one cell to the nth direction calculated by transferring to the cell in the nth direction?
hi Aidan your videos helps to clear the concepts about the models use in cfd can you pls explain the flow separation and adverse pressure effects in cfd?
this was goot to hear, would you happen to know a method to simulate a laser interacting with water in fluent using a radiation model heating up water in a transparent plastic container?
Hi AIdan. I think at 22.45 min, in the Eq. 17, delta_omega should have a subscript j,1 or j,i in general. Since, the solid angle between different beam directions are different. Owing to this, at 23.17, the delta_omega would not come out of the parentheses as common in Eq. 18.
Thanks for a very clear presentation! However, I'm left confused how we actually (numerically) *solve* the equations? Are the equations (in this case 8, if there's 8 beams) not coupled because of the scattering? At a point "r", to know how much radiation is scattered into the direction "s1" from all the other directions s2,s3.., don't we need to solve those other beams first?
Hi Aidan, is the RTE you shown in the eighth slide a bit wrong ? The sigma in the last term should be substituded by sigma sub s in which is shown in other literature.
!!!!!! I really need help in my attempt to simulate the working inside an electrical resistance furnace, I am looking forward for guidance. Any help would be much appreciated.
Without going into too much detail you can think of them as 'direction resolution'. If you think of radiation as a set of beams, how many beams are there? Finer pixelation = more beams = more accuracy + slower calculation
That's pretty hot! I think you would have to do quite a specific literature search to find what you are looking for. Alternatively you could do a sensitivity study? (Try out different values and see how it affects your solution)
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In the 6:00, for the scattering effect calculation ( the second term on the right), it should be sigma_s/4pi not sigma/4pi. Thank you for your great video.
Well spotted. Thanks!
Comment pinned 👍
Endorsed your point view " it is challenging and really tough to put it together". Though I am an advanced level user of discrete Ordinate (DO) model and published impact factor research articles using DO model. But your explanation is simple, structured and easily comprehensible. My salutation to you. Keep it up.
I have used DO quite a lot and I was familiar with most of the concepts you have mentioned but still, it was awesome friend. Hope to see more of you
Extremely helpful presentation, cleared all my doubts. Many thanks!
Thank you very much, sir. I m definitely buying you a couple of pints after submitting my master thesis.Hats off to your invaluable work in youtube.
Greetings from Spain.
Nice lecture. It would be great to see some worked numerical examples to look on a practical solution and its interpretation.
Great help as always Aiden, thank you very much. Great to have someone work through and summarize the loads documentation out there.
I was searching for some good Resorces to solve RTE equations. This is amazing.
beautiful video, your methods of explaining terms from the basic level is very helpful
Such a beautiful explanation of such complicated model. Many thanks and Best Wishes.
Hope u will soon create a video on P1 model and the modeling of absorption coeff. and scattering function.
I haven't looked at radiation in a while..it might be time to dust off the radiation stuff again!
Amazing presentation! In just 1 hour (I listened back and forth), my level of understanding of not only DOM, but also RTE has been raised significantly! Thank you!
8:40 Delighted to hear your explanation. It seems clear that the RTE doesn't explicitly describe radiation heating/cooling, which should affect the temperature field. Of course, one can empirically use a "resultant temperature" distribution in space.
Very nice video; thank you! However, the radiation does not only interact with the fluid at the wall. Regions of gas that emit net radiation will get cooler, and those that have net absorption will get hotter. This is captured in the energy equation, which you did not show in this video. The energy equation is coupled volumetrically (not just at the boundaries) to the RTE though a new term in the energy equation, the divergence of the radiative flux. That is calculated by a radiative energy balance on a control volume using each of the I's calculated.
Excellent talk, very well explained. As always love to see your videos. Great work.
Thank you Aidan! This is extremely useful as I am doing a radiation simulation. I have become a patron as I think your textbook will be very helpful while learning CFD. Just go on and upload more video and I will support you as always.
Thank you so much. Really appreciate this
Hi sir, I really appreciate your insightful lectures.
I just don't know how to congratulate u or say thank u to u..which I generally i don't do..i really fund this lecture very much informative and interesting.. Thanks a lot and really really appreciate your efforts..
Thank you so much ! Very helpful information,explaining everything!
thank you, sir! much appreciated!
you have done great job with excellent quality of material. Thank you
Will you do a video on the P1 model in the future? And perhaps a video on when is best to use either S2S, P1 or DO methods. Thanks!
Concise. Really good. Thanks a lot.
Hai Dr. Aidan, nice to listen to your lecture in Quarantine days.. :).. I hope UK is doing well..
Very helpful explanation!
Nice presentation!
Excellent explanation!!!! Thank you very much.
Thank you very much.
Excellent work brother. no words to tell
great content as always!
cant wait for your new videos!
great content as always!
have you considered doing any video on the energy cascade for turbulence and subsequent FFT analysis? always struggled getting this set up correctly
I will probably cover this when i do the LES video 🙃 but yes! Good idea
Hi, very interesting theory about the model but I have a question. Where can I get values of properties material such as concrete or sidewalk for DO model ( scattering, absorption and refractive index)? Could you provide them if you have it please?
Regards
30:15 For gases, the refractive index can be approximated as unity, but the emission coefficent, or emissivity, may not be equal to absorption coefficent.
Very nice talk indeed. Why is the absorption within the media not taken into account when looking at the sources/interaction with the temperature, e.g. As an additional volumetric source? Since the intensity is changing doesnt that the mean the energy needs to go somewhere?
I agree, The medium should heat up since it is participating in the radiation. How will that happen if the radiation only interacts at the walls? The absorbed radiation and the emitted black body radiation at a point should participate in the energy balance at that point.
@@moma8956 You are correct. The radiation does not only interact at the wall. Regions of gas that emit net radiation will get cooler, and those that have net absorption will get hotter. This is captured in the energy equation, which he did not show. That is absolutely coupled volumetrically to the RTE though a new term in the energy equation, the divergence of the radiative flux.
Really Really Good. Thanks a lot!!!!
In the fluid region where gas particles exist, is the radiation from one cell to the nth direction calculated by transferring to the cell in the nth direction?
brilliant as always ;)
hi Aidan your videos helps to clear the concepts about the models use in cfd can you pls explain the flow separation and adverse pressure effects in cfd?
this was goot to hear, would you happen to know a method to simulate a laser interacting with water in fluent using a radiation model heating up water in a transparent plastic container?
Hi AIdan. I think at 22.45 min, in the Eq. 17, delta_omega should have a subscript j,1 or j,i in general. Since, the solid angle between different beam directions are different. Owing to this, at 23.17, the delta_omega would not come out of the parentheses as common in Eq. 18.
I too think the delta omega should not come out as a constant in the way it is shown. en.wikipedia.org/wiki/Discrete_ordinates_method
Hi Sir would like a video on ray tracing radiation model used in Ansys
Great lecture. Thank you!
It is indeed nicely presented.
A quick question. If I have a model with air as a gas, I am fine with using S2S model since air is basically N2 and O2.
Yep, air can be considered non participating, so S2S is fine
Thanks for a very clear presentation! However, I'm left confused how we actually (numerically) *solve* the equations? Are the equations (in this case 8, if there's 8 beams) not coupled because of the scattering? At a point "r", to know how much radiation is scattered into the direction "s1" from all the other directions s2,s3.., don't we need to solve those other beams first?
Hi Aidan, is the RTE you shown in the eighth slide a bit wrong ? The sigma in the last term should be substituded by sigma sub s in which is shown in other literature.
!!!!!! I really need help in my attempt to simulate the working inside an electrical resistance furnace, I
am looking forward for guidance. Any help would be much appreciated.
Hi! Thank you for your nice video, I have a question: exactly what are pixelation parameters used for? Thank you very much again :)
Without going into too much detail you can think of them as 'direction resolution'. If you think of radiation as a set of beams, how many beams are there? Finer pixelation = more beams = more accuracy + slower calculation
It still difficult to understand and use it. How can we know those three material constants you'v mentioned? Is there any reference?
sir can you explain what is the difference between internal emissivity and external emissivity??? please..
Great lecture. At 6:00 we have the stefan Boltzman constant in W/m2/K but I think it is W/m2/K4 would you confirm? Thanks!!
Will you please upload other methods to solve RTE. ??
how should i implement it numerically. I saw a numerical code of DOM it has some gauss quadrature thing in it.
How we can guess the absorption and scattering coefficient of steel at 1500 K?
Thank you in advance :)
That's pretty hot! I think you would have to do quite a specific literature search to find what you are looking for. Alternatively you could do a sensitivity study? (Try out different values and see how it affects your solution)
hi. Brother can you please upload videos on P1 radiation model and Rosseland Radiation model.
Can you do a video on K - Omega Model.?
As usual, Thank you for the videos.. :)
Would you please tell me the program you use to record the videos?
Could you put some lectures on FSI?
Hopefully yes. FSI is very difficult so it will take me some time to put together some good slides!
Please come up with K-omega model
Can you suggest some of the books for radiation
Radiative Heat Transfer by Michael Modest is very good. So is Thermal Radiation Heat Transfer by Howell et al.
thank you!!
cooool
Great! ;)
He looks like goku