We study the Riemann problem for the system of conservation laws of one dimensional isentropic gas dynamics in Eulerian coordinates. We construct solutions of the Riemann problem by the method of self-similar zero-viscosity limits, where the self-similar viscosity only appears in the equation for the conservation of momentum. No size restrictions on the data are imposed. The structure of the ob...

We present the general analytic solution of a viscous gas ring around a central mass. This solution is used to test a further development of the smoothed particle hydrodynamics (SPH) algorithm, which is capable of simulating problems with physical viscosity (here: with kinematic viscosity). We discuss some SPH simulation results and conclude some fundamental properties of the algorithm. c © 199...

We calculate the bulk viscosity of the massive pion gas within unitarized chiral perturbation theory. We obtain a low-temperature peak arising from explicit conformal breaking due to the pion mass and another peak near the critical temperature, dominated by the conformal anomaly through gluon condensate terms. The correlation between bulk viscosity and conformal breaking supports a recent QCD p...

Almost all available literature correlations to predict the volumetric gas /liquid mass transfer coefficient, kLa in agitated reactors are systemsor operating conditions-dependent. In this study, two back-propagation neural networks (BPNNs), one dimensional and one dimensionless were developed to correlate kLa for numerous gas /liquid systems in both surface-aeration reactors (SAR) and gas-indu...

By using chiral perturbation theory and the Uehling-Uhlenbeck equation we compute the viscosity of a pion gas, in the low temperature and low density regime, in terms of the temperature and the pion fugacity. The viscosity turns out to be proportional to the square root of the temperature over the pion mass. Next to leading corrections are proportional to the temperature over the pion mass to 3/2.

Hydrogen is seen as one of the important energy carriers of the future with potential to reduce local as well as global warming. The main by-product of the combustion of hydrogen in air is water vapor and trace quantities of oxides of nitrogen. An experiment was conducted to study the impact of hydrogen/natural gas blends on performance, thermodynamic efficiency and exhaust gas emissions in ...