Glass viscosity calculations debunk the myth of flow in medieval windows (2017)

Re:Glass viscosity calculations debunk the myth of flow in m... by pfdietz on Thursday October 29, 2020 @10:59PM (#24938676)

I didn't say the compression was isothermal.

The parent is not correct. Compression occurs at a shock, but this is not heating due (solely) to adiabatic compression. This is clearly seen by considering the case where mach number goes to infinity: in that limit, the fraction of heating due to compression goes to zero (as the gas density remains below some finite limiting value.) What is causing heating is a dissipative process in the shock itself. This dissipative process is more akin to friction than it is to compression.

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Re:Glass viscosity calculations debunk the myth of flow in m... by ThenAsNow on Thursday October 29, 2020 @11:19PM (#24938784)

Parent just said "compression heating" which no one takes as a claim of isentropic compression. Shock-driven compression still qualifies as compression.

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Re:Glass viscosity calculations debunk the myth of flow in m... by pfdietz on Thursday October 29, 2020 @11:22PM (#24938802)

This has just defined shock heating as compression heating. But as I argued elsewhere, that makes no sense, since the compression at a shock is bounded by a finite maximum value regardless of the mach number.

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Re:Glass viscosity calculations debunk the myth of flow in m... by bollu on Friday October 30, 2020 @06:42AM (#24940906)

This is very interesting, is there a textbook for this?

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Re:Glass viscosity calculations debunk the myth of flow in m... by bernulli on Friday October 30, 2020 @06:27PM (#24947465)

I haven't seen any of pfdietz' arguments in a book.

But ThenAsNow already recommended the excellent "Modern Compressible flow" by J.D. Anderson, and, in extension, I can recommend "Hypersonic and High-Temperature Gas Dynamics" by the same author.

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