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A comment on Simulating an Entire Car Engine (yes, it makes noise) [video].

Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by modeless on Saturday August 06, 2022 @12:04PM (#32369236)
80,000 Hz rigid body simulation! That's amazing. Seems like the only output of the simulation that's used in sound generation is the graph of exhaust pressure. He's adding white noise to the output. I wonder if it would be possible to replace the white noise by reading the vibrations of the various rigid bodies directly out of the simulation.
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Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by goldenkey on Saturday August 06, 2022 @05:47PM (#32371857)
They are rigid, so they wouldn't vibrate, no elasticity/100% dampening, would they?
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Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by modeless on Saturday August 06, 2022 @06:54PM (#32372324)
They won't deform but they still move and collide and that could be used to generate sound. Deformations could also be modeled by splitting parts into pieces connected by compliant joints.
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Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by tekknik on Sunday August 07, 2022 @07:53AM (#32375774)
The sound from an engine doesn’t come from it rattling, tolerances in modern engines are very tight. Sound comes from the explosions.
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Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by Too on Monday August 08, 2022 @04:10AM (#32383353)
Due to inertia of the piston and minor velocity difference of moving up vs down in a cranking geometry, an ICE will be unbalanced and generate vibrations. Called primary and secondary balance.

This has nothing to do with tolerance, but yeah I’m not talking about rattling either, just vibrations.

Unless you have a V8, where all this unbalance is cancelled out by opposing movement on the other side of the engine.

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Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by tekknik on Monday August 08, 2022 @09:02AM (#32384901)
It’s more to do with crankshaft design than piston count. Either way, engines have had dampeners / balancers on them since before either of us were born. So again, the sound is coming from the explosions, not the vibrations.
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Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by modeless on Sunday August 07, 2022 @10:35AM (#32376790)
I'm sure people are interested in simulating more than modern engines with this.
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Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by matt-attack on Tuesday August 09, 2022 @10:34AM (#32398582)
What about valve clatter? I’m positive you can hear that.
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Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by aliswe on Saturday August 06, 2022 @07:21PM (#32372496)
rigid means they are not jointed, i think, not that they necessarily dont vibrate...
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