There is a powerful movement nowadays supporting the “democratization of CFD”.
Far and fore most I want to declare that I would be ultimately happy when the day shall come and it appears that it is just around the corner.
Nonetheless, lately I read quite an interesting post (by Keith Hanna – Mentor Graphics) about the “Democratization of CFD“. I do agree that a very strong case was beautifully presented. Mentor Graphic’s FloEFD uses a 2-eq k-ε turbulence model with a switching function designed to match the simulation to “thin/thick” boundary layer concept. As I was rolling my LinkedIn feed I came across a post presenting a colorful picture of direct cooling of a highly populated PCB at I believe to be a large enough Reynolds to be considered turbulent (as no natural convection was displayed, meaning it’s not the dominating mode of heat transfer), perhaps the flow is believed to be a result of an external fan or ECS.
I couldn’t ignore the post inviting the reader to watch how a k-ε turbulence model based on the “Boussinesq Hypothesis” could possibly solve a flow over one square cube (to all its unsteady features and massive separations), let alone an array of such. unless the expectation for results resolution tends to none…
well, A flow over an attached cube at a Reynolds number of 7250 shall look something like that . Still, making a case for such simulations relies on the true fact that mechanical designers, once totally cut out of the loop regarding CFD shall now be able to engage with the simulation at the most early stages of the workflow.
Referring to SRS, it is quite obvious that in order for LES to be widespread in the design process, it clearly needs to be much more accessible to non-proficient practitioners.
In my post “Let’s LES” I have reviewed some of LES mandatory set of tools without which the credibility of the simulation is doubtful at best. When a non-proficient practitioner tries to perform an LES, there are many instances of which being able to construct an animation of a time-varying flow that looks like a turbulent flow seems very satisfying. However, this offers no guarantee that the appropriate grid resolution has been used, spatial and temporal schemes have been selected, boundary conditions (especially time-varying, turbulent containing inflow conditions) are proper, etc’… CFD practitioners have to be educated to control a much different set of tools than those they were used to with RANS (and other low fidelity methodologies) to actually achieve the added benefit that LES could provide.
Nonetheless, acknowledging the limitations (speed and ease of use at the price of accuracy), one might certainly claim that the days of “democratization of CFD” are here and with possible increase in the utilization computing resources (dedicated algorithms, GPUs, etc…) they shall be much more vivid in the near future.