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The development of numerical solvers able to simulate compressible two-phase flows is still a great challenge in computational fluid dynamics. The interaction between acoustic waves and interfaces is of major concern for several engineering and biomedical applications, among which atomization in combustion chambers, cavitation problems, underwater explosions and bubble shock interactions. For instance, there are experimental evidences that acoustic waves can have an important effect on the atomization process, and this could have a great impact on combustion. However, usual approaches for DNS of primary atomization are based on incompressible solvers and therefore are not able to capture the propagation of acoustic waves and therefore cannot be used to simulate such phenomena. The numerical problem associated with the simulation of compressible two- phase flows is challenging, mostly because of the huge spatial variations of the speed of sound and the corresponding low Mach number in the liquid phase. In the present work, a numerical solver able to study subsonic compressible two-phase flows is presented. The solver is based on a complete formulation of the Navier-Stokes equations with real fluid equations of state, which are solved with a semi-implicit projection method. It is shown that the solver can handle a large range of compressible subsonic flows, both for a single phase or for two phases, as the flow induced by free convection, a bubble expansion in isothermal or isentropic conditions, and interaction between acoustic waves and liquid-gas interfaces. Eventually, attention will be given to the simulation of a water droplet in air, under the excitation of a stationary acoustic wave. It is also shown that the solver exhibits equivalent performances as an incompressible solver in configurations where compressible effects have no effects.

Objectives The use of chest physiotherapy (CP) has not, to date, been shown to be effective in the care of infants hospitalized for bronchiolitis. However, it has not yet been studied in outpatient settings. The aim of our study was to examine the short-term benefit of CP with the increased exhalation technique (IET) on the respiratory conditions of nonhospitalized infants. Methods Our research consisted of a multicenter, randomized, controlled, single-blind study of infants under 1 year old. A decrease in the severity score of the infants' respiratory condition was compared between two groups: one receiving CP and one without CP. Eighty-two infants were randomized: 41 in the CP group and 41 in the control group. Blinded assessors determined the Wang Clinical Severity Score at inclusion (T0) and 30 minutes later (T1) for each group. Results Improvement in the severity score was observed for 29 infants (70.7%) in the group receiving CP, compared with 4 infants (9.76%) in the control group (p Conclusion For outpatient care of infants with bronchiolitis, the results of this study suggest that CP with IET leads to a short-term improvement of mucus airway obstruction parameters.