After GPS, ISRO Is Now Working On World's Most Efficient Weather Prediction Satellite!

[Roybot]

one thing i have noticed that it always takes more than one or two days for you to respond.
i don't know why someone who knows fluid mechanics to respond takes more than one day.
parroting the same thing i said back to me.
contradicting saying 3d flow cannot be computed because of present generation technology. and next few lines saying it can be computed with DNS. Thinking that repeating DNS, LES makes a person knowledgeable. I hope you at least know the full form of DNS,LES.
typical troll behaviour
have you ever worked on a large set of data to talk about computation?
I had made only two points giving the reason for unpredictable 3d fluid flow.
you are stuck with the first point boundary layer separation.
why would i give answer for a technically challenged person like you?
why don't you sit down and analyse,what kind of cock and bull story was your first post.
stop quoting me further i do not have time for a technically challenged person like you ,troll







Typical troll behaviour

Maybe he has a real job, maybe.

 

[thinkingcap81]

one thing i have noticed that it always takes more than one or two days for you to respond.
i don't know why someone who knows fluid mechanics to respond takes more than one day.
parroting the same thing i said back to me.
contradicting saying 3d flow cannot be computed because of present generation technology. and next few lines saying it can be computed with DNS. Thinking that repeating DNS, LES makes a person knowledgeable. I hope you at least know the full form of DNS,LES.
typical troll behaviour
have you ever worked on a large set of data to talk about computation?
I had made only two points giving the reason for unpredictable 3d fluid flow.
you are stuck with the first point boundary layer separation.
why would i give answer for a technically challenged person like you?
why don't you sit down and analyse,what kind of cock and bull story was your first post.
stop quoting me further i do not have time for a technically challenged person like you ,troll







Typical troll behaviour

As you hopefully notice, a couple of people have asked me not to reply to you. But i shall write this last post, and it is not just aimed at you.

I cannot post quickly because the institute where i am working has blocked defence.pk, i don't know why. The sys admins there are as useful as you. I reply when i am not at my work-place.

I am saying i know more fluid mechanics than you, i am not claiming to be an expert unlike your claims.

In your inability to respond to me, you are missing the point. If you have the correct set of governing equations and good initial and boundary conditions, then DNS simulations which are done at the resolution of the order of the Kolmogorov scale gives you the ability the compute these equations with a high degree of reliability. It is another issue that almost all flows of interest cannot be done given the computational facilities that are available in the market today - and i mean the most powerful supercomputers.

So, to circumvent such high computational requirements, we use RANS, LES models which have built in rational equations etc. which seek to predict certain fluid flows - and these models can fail for fluid flows for which they are not designed to simulate.

Forget rational approximations, General Circulation Models (GCMs) that are used to simulate the Earth's climate system actually have tunable parameters that have been set solely to get a climate that looks realistic in a very mean sense. They cannot even get present day weather and climate correctly - hence their wildly differing future climate predictions - see the IPCC reports to have a feel. But these GCMs have their uses - they at least tell us that it is very likely that we humans are responsible for such rapid climate change. They tell us that we need to be responsible and think of mitigation strategies. Weather models have helped our country so much by their predictions.

Not one climate/weather scientist worth his salt will even speak of flow separation as a hindrance in getting better predictions. Flow separation is important in aerodynamics, aircraft jet engines etc. because they cause load imbalances, wakes, problems with drag calculations, vibrations, compromise structural structural integrity and many others which folks with much better capability than me know about.

Just because flow separation is important in one area it is ridiculous to say that it is of vital importance in other areas.

Where i am working is irrelevant, just give a rebuttal to my points and answer my queries challenging your claims.

@thinkingcap81 , Thank you for your well organized and highly informative posts, they sparked my interest in fluid mechanics. I would like to learn a lot more about the subject, and if you could suggest me some books on the subject that could help an ignorant like me to understand how to predict fluid behavior, I'd be grateful to you.

P.S. Why even bother replying to condescending time wasters like that @asiaticlion in here?

Thanks @Not Sure and @Roybot for having the patience to read at least some part of my posts - i can tell you both that i don't have that much patience. My work itself saps my concentrating abilities.

@Not Sure It is very difficult to say which book is suitable. Everyone has a certain preference of books which makes them comfortable. Because of my less than adequate education till a certain level I had lots of difficulties in even understanding a suitable place to start.

I can only tell you my experience. Fluid mechanics requires basic mechanics and basic calculus as a prerequisite. If you have that then it will depend on your basic mentality, that is, whether you are physics or engineering oriented. i'm just telling basic books - try Physical Fluid Dynamics by Tritton, or Elementary Fluid Dynamics by Acheson if you are of physics mindset. Else Fluid Mechanics by F. M. White if you are more inclined towards engineering - there are lots of similar good books at at BE/BTech level. After completing a basic level this you can yourself judge which advanced books work best for you.

Please note that i am just giving some suggestions, you may not like them. But whatever book you choose try to solve problems given at the end of the book or chapter. Solving problems will give you knowledge, capability and confidence. There are very few people who are gifted and have a feel of physical phenomena and mathematics - for the rest like me its a long haul.

Btw in the next 3-4 months i am planning to read Physical Fluid Dynamics by Tritton. Right now i'm studying An introduction to Mechanics by Kleppener and Kolenkow.

 

[thinkingcap81]

It was me who said in the first post and i quote"all 3 dimensional fluid flow model give approximate result as there are many variables to calculate the flow" you are parroting the same thing that i said.

Your first post was full of cock and bull story.
Why don't you analyse your post.

Prove that there is no boundary layer separation of fluids occurring in nature.With temperature, pressure, viscocity gradient etc between various fluid there is no boundary layer separation occurring in nature.
There is no ideal 3d fluid flow occurring in nature.

Oh my dear man! Show me where i said that that there is no boundary layer separation occurring in nature. I said that flow separation is not an important factor in deciding weather and climate predictability. No competent weather and/or climate scientist will say that they are primarily hampered by lack of understanding of when and how flow separation occurs in weather phenomena.

You had said in post #7 that 'the answer is there is no way 3 dimensional fluid flow can be predicted accurately, when there is boundary separation. all 3 dimensional fluid flow model give approximate result as there are many variables to calculate the flow. hence weather forecast throughout the world even USA can go wrong'.

Your post #7 was in response to what i had said in post #6 that we do not even know the all the equations properly, and i said that this is a very important reason that hampers predictions. Your first sentence in post #7 implies that 'boundary separation' (due to 'many variables to calculate the flow') is important for weather and climate predictability. I simply asked you to provide solid proof of the primal importance of 'boundary separation'.

For boundary layer separation, in many cases we know well the governing equations but if our modeling is wrong we won't simulate separation correctly. This is not the case for climate models where we are not even getting many governing equations correctly - this hampers reliable long-term forecasts.

Please do not be so condescending, you won't gain friends and respect this way.

Have a nice day!