Numerical Investigations of Pseudo-Shock Waves in Variable Cross-Section Ducts

Abstract

The Pseudo-Shock Wave (PSW), which appears when supersonic flow in duct decelerates to subsonic, is a complicated process due to the interaction between boundary layer and shock wave. It significantly affects the performance and efficiency of flow devices. In this paper, PSW in two kinds of variable cross-section ducts, edge-varied and corner-varied, was investigated through CFD numerical simulation. Compared to the rectangular duct, a shorter and wider separation region is appeared in the corner of the edge-varied duct while the strongest separation is laterally propagated across the entire plane of the corner-varied duct's side wall. This makes the performances of varied ducts different from traditional constant cross-section ducts.

Theoretical formalism of radiative jet energy loss in a finite size dynamical QCD medium

“…It is important to note that, similarly to [8], each individual diagram that contributes to the energy loss in a finite size dynamical QCD medium diverges logarithmically in the limit of zero transverse momentum of the exchanged gluon, q → 0. The reason for this divergence is that in a dynamical QCD medium both transverse and longitudinal gluon exchange contribute to the radiative energy loss [35]. While Debye screening makes the longitudinal gluon exchange infrared finite, transverse gluon exchange causes a well-known logarithmic singularity [17] due to the absence of a magnetic screening [36].…”

Momentum broadening of a fast parton in a perturbative quark-gluon plasma

“…where ∆p T (x + ) = p T (x + ) − p T (0). Equation (17), which is the main result of this section, has been derived in a specific gauge and the righthand side of the equation is, in general, gauge dependent. The gauge independence can be restored by inserting the Wilson line between the fields F µ− a (y + 1 ) and F ν− a (y + 2 ) in the correlation function F µ− a (y + 1 )F ν− a (y + 2 ) .…”