For every total recursive time bound t, a constant fraction of all compressible (low Kolmogorov complexity) strings is t-bounded incompressible (high time-bounded Kolmogorov complexity); there are uncountably many infinite sequences of which every initial segment of length n is compressible to log n yet t-bounded incompressible below 1 4n− log n; and there are countable infinitely many recursiv...

This contribution is devoted to the mathematical modelling of a compressible viscous fluid flow through a 2-D model of the male rotor-housing gap in screw machines. Numerical solution of the nonlinear conservative system of the compressible Navier-Stokes equations is obtained by means of the cell-centred finite volume formulation of the explicit two-step TVD MacCormack scheme proposed by Causon...

The ADINA program can be used for analyses of fluid flows fully coupled with structures. Fluid flows can be modeled as incompressible, slightly compressible, fully compressible and porous media flows. Both iterative (partitioned) and direct (simultaneous) solution procedures can be used. The capabilities available in ADINA are briefly summarized and various experiences regarding the use of the ...

We present two phenonmenological subgrid-scale (SGS) models for large-eddy simulations (LES) of compressible turbulent flows. A nonlinear model and a stretched-vortex model are tested in LES of compressible decaying isotropic turbulence. Results of LES at 32 resolution are compared to corresponding 256 direct numerical simulations (DNS). We use numerical schemes based on compact differences and...

We define compressive and rarefactive waves and give the differential equations describing smooth wave steepening for the compressible Euler equations with a varying entropy profile and general pressure laws. Using these differential equations, we directly generalize P. Lax’s singularity (shock) formation results in [9] for hyperbolic systems with two variables to the 3× 3 compressible Euler eq...

In the present work, we are interested in the direct numerical simulation of the compressible Euler and Navier Stokes equations at low Mach number regime. First, we propose a review of existing work on the subject in order to identify the issues raised by the simulation of in this kind of flow, and the existing relevant solutions. Then, we will test different selected compressible low Mach solv...

We consider relativistic and ”semi-relativistic” models of radiative viscous compressible Navier-Stokes-Fourier system coupled to the radiative transfer equation extending the classical model introduced in [1] and we study some of its singular limits (low Mach and diffusion) in the case of well-prepared initial data and Dirichlet boundary condition for the velocity field. In the low Mach number...

This paper presents an approach, which combines the conventional finite volume method (FVM) with the lattice Boltzmann Method (LBM), to simulate compressible flows. Similar to the Godunov scheme, in the present approach, LBM is used to evaluate the flux at the interface for local Riemann problem when solving Euler/Navier-Stokes (N-S) equations by FVM. Two kinds of popular compressible Lattice B...

We introduce a practical disk-based compressed text index that, when the text is compressible, takes much less space than the suffix array. It provides good I/O times for searching, which in particular improve when the text is compressible. In this aspect our index is unique, as most compressed indexes are slower than their classical counterparts on secondary memory. We analyze our index and sh...