Tag: turbulence modeling

  • Formula 1 Aerodynamics

    [original media no longer available]

    Computational fluid dynamics (CFD) and the advent of supercomputing have forever changed the way engineers design. Here the use of CFD in the design of Formula 1 racing cars is discussed. Although CFD is used by many companies in place of wind tunnel testing, each method has its advantages.  CFD provides information about all flow quantities at all points in the flow but can only do so with an accuracy dependent on the grid and models used.  It remains impossible to solve the equations of motion exactly for any problem of practical application because the computational cost is simply too high; instead software packages like FLUENT utilize turbulence models that approximate the physics.  Wind tunnel testing, on the other hand, is physically accurate but typically yields only limited data and flow quantities due to the difficulty of instrumentation. (Video credit: BBC News; submitted by carhogg)

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  • Volcanic Turbulence

    Volcanic Turbulence

    One of the characteristics of turbulence is its large range of lengthscales. Consider the ash plume from this Japanese volcano. Some of the eddy structures are tens, if not hundreds, of meters in size, yet there is also coherence down to the scale of centimeters. In turbulence, energy cascades from these very large scales to scales small enough that viscosity can dissipate it. This is one of the great challenges in directly calculating or even simply modeling turbulence because no lengthscale can be ignore without affecting the accuracy of the results. #