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Titolo: TRIPLESHOCK ENTROPY THEOREM AND ITS CONSEQUENCES
Autore: HENDERSON LF; MENIKOFF R;
 Indirizzi:
 8 DAMOUR AV,E LINDFIELD SYDNEY NSW 2070 AUSTRALIA CNRS,AEROTHERM LAB F92190 MEUDON FRANCE TOHOKU UNIV,INST FLUID SCI,SHOCK WAVE RES CTR SENDAI MIYAGI 980 JAPAN BEN GURION UNIV NEGEV,DEPT MECH ENGN IL84105 BEER SHEVA ISRAEL LOS ALAMOS NATL LAB,DIV THEORET LOS ALAMOS NM 87545
 Titolo Testata:
 Journal of Fluid Mechanics
,
volume: 366,
anno: 1998,
pagine: 179  210
 SICI:
 00221120(1998)366:<179:TETAIC>2.0.ZU;2W
 Fonte:
 ISI
 Lingua:
 ENG
 Soggetto:
 MACH REFLECTION; WAVE REFLECTIONS; STEADY FLOWS; TRANSITION; RECONSIDERATION; INTERFACE; EMISSION; FRONTS;
 Tipo documento:
 Article
 Natura:
 Periodico
 Settore Disciplinare:
 Science Citation Index Expanded
 Science Citation Index Expanded
 Citazioni:
 42
 Recensione:
 Indirizzi per estratti:



 Citazione:
 L.F. Henderson e R. Menikoff, "TRIPLESHOCK ENTROPY THEOREM AND ITS CONSEQUENCES", Journal of Fluid Mechanics, 366, 1998, pp. 179210
Abstract
For a convex equation of state, a general theorem on shock waves is proved: a sequence of two shocks has a lower entropy than a single shock to the same final pressure. We call this the tripleshock entropy theorem. This theorem has important consequences for shock interactions. In one dimension the interaction of two shock waves of the opposite family always results in two outgoing shock waves. In two dimensions the intersection of three shocks, such as a Mach configuration, must have a contact. Moreover, the state behind the Mach stem has a higher entropy than the state behind the reflected shock. For the transition between a regular and Mach reflection, this suggests that the von Neumann(mechanical equilibrium) criterion would be prefered based on thermodynamic stability, i.e. maximum entropy subject to the system constraint that the total specific enthalpy is fixed. However, to explain the observed hysteresis of the transition we propose an analogy with phase transitions in which locally stable wave patterns (regular or Mach reflection) play the role of metastable thermodynamic states. The hysteresis effect would occur only when the transition threshold exceeds thebackground fluctuations. The transition threshold is affected by flowgradients in the neighbourhood of the shock intersection point and the background fluctuations are due to acoustic noise. Consequently, theoccurrence of hysteresis is sensitive to the experimental design, andonly under special circumstances is hysteresis observed.
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Documento generato il 23/11/20 alle ore 20:13:12