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Philip Sorensen February 19, 2007 14:45

Consultant w/ Expertise in Aerodynamics & CFD
ATI is a small technology search firm. We initiate alliances between our clients, typically large companies seeking external technology or expertise, and outside firms or consultants that can help.

Here is the request --

Identification of Technical Consultants with Expertise in Aerodynamics and CFD Who can Identify Factors that Contribute to the Drag on Small, Non-symmetric Blunt Objects:

For a current project, we are seeking consultants with expertise in aerodynamics and CFD who can predict drag forces and identify specific geometric features contributing to the total drag (pressure and friction drag) on small (< 5" dia.) non-symmetric blunt objects of specific and detailed geometry (CAD models of multiple variants supplied). The goal is to analytically identify the detailed geometry having the lowest drag among multiple geometry variants and predict relative affects on speed. Objects are traveling at a velocity of approximately 100 mph and rotating at approximately 300 rpm (low speed, unsteady aerodynamics, standard atmosphere). The need is to be able to predict small changes in drag (total drag force is < 2 lbf, may need to resolve 1/10's of a lbf) caused by subtle changes in object shape that result in changes to speed of about 0.3%, for a constant propulsive input.

We are seeking experts who you capable of carrying out this analysis, and who further would be able to provide input into these questions:

Is this problem statement solvable given current state of the art in CFD and the difficulty of simulating turbulent flow? What is the level of difficulty on a scale of 1-10? What CFD code would you use?

Please let me know if you are interested and we can discuss or email next steps.

Thank you for your consideration.

== Advanced Technology Innovations, Inc. 100 Petaluma Blvd. N, #303 Petaluma, CA 94952 Ph: 707-285-2020 Fx: 707-988-2616 Email:

Mr.Nantaratn Kananai February 21, 2007 03:52

Re: Consultant w/ Expertise in Aerodynamics & CFD
To Philip

I interested in this work. I think this work so challenge me. I normally use software Fluent to solve CFD problem. For your problem, you can use Fluent software as the solver. The main problem is the stablity of the simulation which depends on mesh-grid generation to satisfy cell-reynold number. I recommend to use Fluent because it has MG(multi-grid). For aero-dynamic problem, you need a lot of memory for a large number of mesh.

Finally, I interested in you work. Could you please send me more detail, cad-geometry or discussion. I will waiting for your problem.

Regards, Nantaratn

Philip Sorensen February 21, 2007 16:01

Re: Consultant w/ Expertise in Aerodynamics & CFD
Thank you for your interest, Nantaratn. I am in the process of seeing if I can get a CAD drawing of the geometry from my client and will keep you posted.

BTW, where are you based?

Best regards, -Phil ==

Advanced Technology Innovations, Inc. 100 Petaluma Blvd. N, #303 Petaluma, CA 94952 Ph: 707-285-2020 Fx: 707-988-2616 Email:

Jonas Larsson February 21, 2007 18:32

Re: Consultant w/ Expertise in Aerodynamics & CFD
Simulationg small changes of friction and pressure drag on a blunt rotating object sounds a bit tricky, especially if the object is shaped so that you have separation from a blunt surface where the separation point can move freely. You can use most commercial codes for this type of problem though, but there is no guarantee that you'll get correct results without any kind of validation from experiments using a similar object.

I'd start with having an experienced aerodynamicist look at the different objects and give his opinion of which will produce the least drag. CFD can then be used to look at the details of the most promising shapes. Make sure that the one performing and analysing the CFD results is aware of the problems associated with this type of simulations though (predicting correct separation points, possible unsteady wake patterns, predicting turbulent transition and guessing correct inlet conditions, predicting the correct effect of rotation, ...)

Abhishek Jain February 26, 2007 06:10

Re: Consultant w/ Expertise in Aerodynamics & CFD
Dear Dr Sorenson,

We would wish to introduce ourselves as a CFD company that has built its own CFD software and is well versed in Aerodynamics applications ranging from hypersonic flow upto Mach 10 to flow around a parachute that is incompressible. We have been part of various design projects for Aerospace vehicles (that I cannot mention here) for varying range of Mach Numbers. Besides CFD we also have a team that can do Dynamics and Controls of various aerospace vehicles including parachutes (This code is the first of its kind in the world with 9 Degree of Freedom capability). Our team has scientists of international acclaim whose CV I am sending to you on personal mail to apprise you of the quality manpower we have to deal with challenging problems. We hope we can work together.


Abhishek Jain

Zeus Numerix

Philip Sorensen February 27, 2007 16:01

Re: Consultant w/ Expertise in Aerodynamics & CFD
thanks very sound most interesting and i'll look forward to rec'g the info you mentioned. Best regards, -Phil

Philip Sorensen February 27, 2007 17:36

Re: Consultant w/ Expertise in Aerodynamics & CFD
thank you for your helpful input, jonas! Best regards, -Phil

Philip Sorensen February 27, 2007 17:54

Re: Consultant w/ Expertise in Aerodynamics & CFD
Hi Nantaratn, thanks for the reply. Can you provide any background on you or your company so that we might share this with our client? Hopefully in time we'll be able to share more detail as you requested, such as cad-geometry. thank you. -phil

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