Jean-Michel Alimi

Adaptive Smooth Particle Hydrodynamics and Particle-Particle Coupled Codes: Energy and Entropy Conservation

We present and test a general-purpose code, called PPASPH, for evolving self-gravitating fluids in astrophysics, both with and without a collisionless component. In PPASPH, hydrodynamical properties are computed by using the SPH (Smoothed Particle Hydrodynamics) method while, unlike most previous implementations of SPH, gravitational forces are computed by a PP (Particle-Particle) approach. another important feature of this code is that hydrodynamics equations optionally include the correction terms appearing when

Scalar - tensor cosmological models

h(t,\br)

Are Large X-Ray Clusters in Thermal Equilibrium?

is not constant. Our code has been implemented by using the data parallel programming model on CM5(CM). PPASPH has been applied to study the importance of adaptative smoothing correction terms on the entropy conservation. We confirm Hernquists (1993) interpretation of the entropy violation observed in previous SPH simulations as a result of having neglected these terms. An improvement on the entropy conservation is not found by merely considering larger numbers of particles or different

Convergence of scalar–tensor theories towards general relativity and primordial nucleosynthesis

N_S

Constraints on the scalar - tensor theories of gravitation from primordial nucleosynthesis

choices. The correct continuum description is only obtained if the

Thermodynamic evolution of cosmological baryonic gas I. Influence of non-equipartition processes

\bn h

Asymptotic and exact solutions of perfect-fluid scalar-tensor cosmologies

correction terms are included. Otherwise, the entropy conservation is always rather poor as compared to that found for the total energy.

Nonlinear clustering in the CfA redshift survey

We analyze the qualitative behaviors of scalar-tensor cosmologies with an arbitrary monotonic

Upper Limit to ΩB in Scalar-Tensor Gravity Theories

\omega(\Phi)

FORMATION OF LARGE SCALE STRUCTURES OF THE UNIVERSE ON THE CONNECTION MACHINE-2.

function. In particular, we are interested on scalar-tensor theories distinguishable at early epochs from General Relativity (GR) but leading to predictions compatible with solar-system experiments. After extending the method developed by Lorentz-Petzold and Barrow, we establish the conditions required for convergence towards GR at