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hankwang writes:
"For the past couple of days, China's capital has been suffering under severe smog, leaving the sun and skyscrapers barely visible. The highest concentration of small airborne particles (PM2.5) was 0.50 mg per cubic meter, a factor 20 above the Word Health Organization's safe limit. Scientists went as far as comparing this to a nuclear winter. The worst seems to be over for now: today, the monitors are reading 0.180 mg/m3, only a factor 7 above the WHO limit.
The Chinese smog seems to behave differently from the smog in Europe and the US. Existing scientific models developed in the West do not work well. To improve the models and understanding, plans are underway to build a 600 cubic-meter (that's 21,000 cubic ft or 160,000 US gallon) transparent dome as a smog chamber."
[NOTE TO EDITOR: I can't get slashcode to display the mu symbol, so I converted to milligrams] [Ed's Note: Thankyou - but what is it in firkins?]
(Score: 2) by hankwang on Tuesday March 04 2014, @09:38AM
The question is: which software? And then: which settings? Typically, computational fluid dynamics software has many model parameters that need to be set in order to capture the relevant physical effects for the problem at hand, without wasting processing time on effects that do not make a difference. Doing so correctly requires that you have a good grasp of the underlying physics, otherwise it will be garbage in, garbage out. Moreover, once you have this good grasp, it is likely that you can do back-of-the-envelope estimates to see whether what you want to achieve is at all plausible, or likely to be orders of magnitude off.
Part of my job is doing, outsourcing, and reviewing simulations (gas flow, diffusion, thermal, deformation, particle-gas transport, and others) for engineering purposes (not electrostatic gas filtering, though), and have seen many times that simulations produced nonsense results because the elephant in the room was missed, i.e., some dominant physical effect that was not accounted for.
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