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CFD Engineer
Last Activity:
May 23, 2019 at 8:05 AM
Joined:
Feb 27, 2019
Messages:
14
Likes Received:
13
Trophy Points:
3
Gender:
Male
Birthday:
Aug 21, 1983 (Age: 35)
Location:
Chicago, Illinois
Occupation:
Mechanical Engineer, Fluid Dynamicist

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CFD Engineer

Bent Axle, Male, 35, from Chicago, Illinois

CFD Engineer was last seen:
May 23, 2019 at 8:05 AM
    1. There are no messages on CFD Engineer's profile yet.
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  • About

    Gender:
    Male
    Birthday:
    Aug 21, 1983 (Age: 35)
    Location:
    Chicago, Illinois
    Occupation:
    Mechanical Engineer, Fluid Dynamicist
    I'm new to Pinewood Derby,
    Built cars with my son for cub scouts in 2018 and 2019, as well as for my daughters for the parents siblings "Open class" race.
    Took 1st place in scouts and open class both years by a large margin.

    Looking to learn and also provide some engineering and mathematical knowledge and fluid dynamics simulation to the community.

    Some work I have done:
    I wrote a computer script to simulate a cars race times based on car parameters in order to quantify the performance gains seen by different variables. This is probably similar to Doc Jobes "virtual race" program. Right now it is set up for a 42' best track, including the effect of the 48" radius which increases g force and axle friction. It is easily modifiable to any track dimensions.
    It is very detailed, but could always be improved upon via:
    Constant axle coefficient of friction could be updated to be dependent on angular velocity of the wheels.
    Moment of Inertia of car is not taken into account, I'm unsure how to define this mathematically. Any help would be appreciated.

    Right now, I'm simulating the fluid physics of oil filled fluid bearings and the drag and lift provided by the oil at different velocities, and the resulting oil film thickness @ the contact interface.
    I'm starting simple, and plan to make the simulation more complex as information and fluid bearing principals are learned.
    Right now is is purely 2D with a fully oil filled gap.
    I will test the effects of oil viscosity and density on the friction, oil film thickness per unit load vs various RPM, and lift provided by the film.

    Future work should include:
    - Study of initial radial clearance between axle and wheel bore. right now I'm simulating 0.093"/0.098" axle/bore combo which are perfectly smooth.
    - Effect of sand grain roughness values on the surfaces.
    - Full 3D simulation with groove.
    - Partially filled oil and air mixture, which should be able to show the effects of oleophilic and oleophobic surfaces. This will take some preliminary model validation of the oleophilic/oleophobic surface behavior and contact angles.
    - Combination of Previous simulations, and perhaps more.
    - Real world testing could be conducted after principals are learned. I would probably use a high speed camera to record a spindown wheel with 2oz weight attached and correct for the air drag. therefore estimating friction coefficient as a function of angular velocity. seeing if it agrees with simulations.

    I have also done Computational Fluid Dynamics (CFD) simulations on car bodies, wheels, full cars with and without fenders, etc. I'd like to design an extremely aerodynamic car, which may have to give up some rear weight bias, and simulate (using my virtual race program) if the aerodynamic advantage outweighs the Center of mass advantage. Initial calculations show it is very plausible on a 42' track. Longer tracks would lend the advantage to aerodynamics more than COM, so this is a track dependent comparison.

    I've done calculations on Wheel M.O.I. and dimensions to calculate where to take material off (rule dependent) and how it affects race times using the virtual race program. It is quite complicated, Several variables are affected when changing a wheels OD, such as increased angular velocity (increased friction), reduced air drag, lower COM and more.

    I find this to be a very intriguing hobby, definitely one of the most physics complex, and a mathematical challenging.
    Hoping to learn from some veterans, and hope I can possibly help them as well.