The smoke-filled dog days of summer

This summer has been a bad one for wildfires and the resultant smoke filling the city, today is no exception and the city is blanketed in a thick cloud of smoke. Thick enough that, standing on my balcony, I can barely see buildings in my neighbourhood through the gloom. I've taken to habitually checking the smoke forecast before going outside and doing anything. In the process it got me thinking about dispersion models and how they work. Beyond forecasting the forest fire smoke, they are used throughout industry to predict where emissions from vents and stacks will go, and also in modeling emergency scenarios (if there is an uncontrolled release of some kind, where will it go?).

tags: smoke, dispersion models, gas, venting,

The pressure field around a bubble

Previously, I figured out the velocity field for creeping flow around a bubble, and made a nice graphic to go with. This time I solved through for the pressure field, and this is what it looks like (along the plane y=0, gauge pressure, all other constants 1) pressure in flow passed a bubble

The derivation …

tags: fluid dynamics, creeping flow, gas,

Creeping flow around a bubble

When fluid flows around a gas bubble, circulation within the bubble dissipates energy away from the interface and the interfacial shear stress is reduced. In this problem (4B.3 Transport Phenomena) I look at what happens when that shear stress is negligible.

creeping flow around a bubble

Flow is coming up along the positive z-axis …

tags: fluid dynamics, creeping flow, gas,

The ideal gas law from Maxwell's velocity distribution

Recently I've been playing around with finding the relations between the microscopic particulars of an ideal gas and the macroscopic observables we all know and love -- in particular the relation between temperature and the average kinetic energy (velocity) of the particles in the gas. We can take the idea further …

tags: kinetic theory, gas,

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