How does heat affect air flow around exhaust ?
 

Just as the title asks, how does heat coming from hot engine exhaust affect the cool oncoming air ?

( I'm thinking of how that air reacts in clouds when cool air meets warm air. )
From what I understand ( or don't ! ) the air creates a vortex.

Intuitively I suspect if airflow was originally laminar, it would increase drag, if not, it might reduce drag. I'm only guessing waiting for those above my paygrade to respond.

Myself also.

Whatever the effect it's probably minimal for an exhaust buried in the underbody. The edge cases would include side pipes at the rocker panel and vertical stacks on a truck.

I gave it my best shot in 2014. Here's vertical stacks with a Coanda nozzle the full height. Because why not?

(Was a picture attached ? I'm not seeing one.)

There spozta wuz....

https://ecomodder.com/forum/member-f...ckup-truck.png

Really more suited to a canopy or camper. But there's a single-wheel trailer and half-tonneau as well.

'exhaust heat / vortex '
 

Considering that cars can be front-engine, inline, transverse, mid-engine, rear-engine; have fully-wrapped exhaust systems, fully-exposed exhaust systems, etc., you might want to choose a specific vehicle that we could think about.
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The 'meteorological ' vortex phenomena require special conditions, usually constrained by convective-available-potential-energy ( CAPE ) along the squall line ( recently 1,300-miles in length ), which limits the warm, moist, equatorial 'Gulf' air's buoyancy and ability to penetrate the cold inversion layer aloft, tapping into 33,000' - 47,000' sub-freezing temperature, high-density air, which is part of supercell dynamics, along with opposing shear winds around 10,000-feet, which create the 'couplet' which aids the ant-cyclonic circulation which will lower to the ground in a wall cloud as the vortex.
All this begins at the poles, with the polar vortex.

Now there is a 'big' picture' approach.

You start with Universe and discard anything at too large or too small a scale; which involves discernment.