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Old 05-12-2010, 12:43 PM   #8 (permalink)
COcyclist
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Join Date: Dec 2007
Location: NW Colo
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TDi - '04 VW Golf
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Side Skirts

Quote:
Originally Posted by lunarhighway View Post

so making air move faster under the car appears to be a good thing based on my interpretation of this data.

Do you mean a boattail that would support this flow direction? if so you're assuming this ourward flow is a good thing, however is causes the air to slow down... what would happen if two partial "side skirts" (or boattails) where placed behind and on the inside of the front wheels crating a duct and preventing the air from moving out. if the air can't move out it can only move backwards so it's speed will remain relatively high and the pressure low. this would stabilise the car in the first place, but also as the low pressure behind the wheels isn't "fed" with air from underneath the car, it might pull in air from the side of the car, thus decreasing the wake. dams in front of the rear wheels designed to guide air under the car might further help decrease the wake.
I added side skirts attached to the rocker panels and small dams in front of the rear tires last spring. My fuel log seems to show an improvement in mpg. From what I have read, it is better to keep air under the car flowing backward to help fill in the trailing wake.
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https://ecomodder.com/forum/showthre...tml#post621801


Quote:
Originally Posted by freebeard View Post
The power needed to push an object through a fluid increases as the cube of the velocity. Mechanical friction increases as the square, so increasing speed requires progressively more power.
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