Why does water splash back onto the hood?

[BodieBronco]

great discussion.
a couple days ago in heavy rain oh the interstate, another car passed me through higher water and splashed me. after they passed and the original splash was over, big amounts of water came back up from the front of my car twice more. I was wondering what was happening. this phenomenon hadn't happened to me in my previous, less boxy/ more aerodynamic vehicles.
thanks!

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[Tigger]

A local road was flooded after a heavy rain so ….

So the official answer of to why water splashes on the hood is ….. Tiggers are fun but dumb!

 

[Mark S.]

So the official answer of to why water splashes on the hood is ….. Tiggers are fun but dumb!

I haven't heard of that Newton's Law, but I like it.

 

[jamaicandave]

It's pretty normal, its the aerodynamics. Could be worse, I get heavy snow here and no matter how much I clean the roof off once it gets milder, I get an avalance of residual snow going down the windshield to the point that it blocks the wiper arms and I have to pull over, open the hood, and clean it out.

 

[Hot Rod Mike]

Remove the hood that will stop it.

 

[Meanderthal]

First rule of comedy, you don't laugh at your own jokes.

 

[Alfa 2407]

Air moving over a surface has a boundary layer. The closer you get to the surface the slower the air moves. In your case, the water on the hood is in the boundary layer, which means the air moving over it is slower than your forward speed. As you brake, you observe Newton's First Law (inertia) in action: the water on the hood wants to continue moving at the same speed it was moving, and its inertia overcomes the relatively slow air movement in the boundary layer and friction of the surface of the hood. Eventually, the water will fall off the front of your hood. When it does it will drop into the slipstream of air moving around your car and out of the boundary layer. Once free of the boundary layer air into the full-speed slipstream, you see Newton's Third Law (action and reaction). While it may appear the water is being blown backward, it is, in fact, the pressure of air from the slipstream forcing the water to move up and slow down while your car continues forward.

Very well said

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