arXiv subjects

Paul Andre Razafimandimby

Publications and source records attributed to Paul Andre Razafimandimby.

8 recordsLinked to original sources

arXiv2025

Time discretization of a semi-discrete scheme for 3D Chemotaxis-Navier-Stokes system driven by transport noise

This work is devoted to the convergence of a time-discrete numerical scheme of a semi-discretization model arising from biology, consisting of a chemotaxis equation coupled with a Galerkin approximation of Navier-Stokes system driven by transport noise in a three-dimensional bounded and convex domain. We propose a semi-implicit Euler numerical scheme approximating the infinite dimensional model, for which we study the well-posedness and derive some uniform estimates for the discrete variables

math.NA↗

arXiv2020

On strong solution to the 2D stochastic Ericksen-Leslie system: A Ginzburg-Landau approximation approach

In this manuscript, we consider a highly nonlinear and constrained stochastic PDEs modelling the dynamics of 2-dimensional nematic liquid crystals under random perturbation. This system of SPDEs is also known as the stochastic Ericksen-Leslie equations (SELEs). We discuss the existence of local strong solution to the stochastic Ericksen-Leslie equations. In particular, we study the convergence the stochastic Ginzburg-Landau approximation of SELEs, and prove that the SELEs with initial data in $\sh^1\times \sh^2$ has at least a martingale, local solution which is strong in PDEs sense.

math.PR↗

arXiv2020

On the 2D Ericksen-Leslie equations with anisotropic energy and external forces

In this paper we consider the 2D Ericksen-Leslie equations which describes the hydrodynamics of nematic Liquid crystal with external body forces and anisotropic energy modeling the energy of applied external control such as magnetic or electric field. Under general assumptions on the initial data, the external data and the anisotropic energy, we prove the existence and uniqueness of global weak solutions with finitely many singular times. If the initial data and the external forces are sufficiently small, then we establish that the global weak solution does not have any singular times and is regular as long as the data are regular.

math.AP↗

arXiv2014

Some qualitative properties of the solutions of the Magnetohydrodynamic equations for nonlinear bipolar fluids

In this article we study the long-time behaviour of a system of nonlinear Partial Differential Equations (PDEs) modelling the motion of incompressible, isothermal and conducting modified bipolar fluids in presence of magnetic field. We mainly prove the existence of a global attractor denoted by $\A$ for the nonlinear semigroup associated to the aforementioned systems of nonlinear PDEs. We also show that this nonlinear semigroup is uniformly differentiable on $\A$. This fact enables us to go further and prove that the attractor $\A$ is of finite-dimensional and we give an explicit bounds for its Hausdorff and fractal dimensions.

math.AP↗

arXiv2014

On stochastic evolution equations for nonlinear bipolar fluids: well-posedness and some properties of the solution

We investigate the stochastic evolution equations describing the motion of a Non-Newtonian fluids excited by multiplicative noise of Lévy type. By making use of Galerkin approximation we can prove that the system has a global (probabilistic) strong solution. This solution is unique and we also prove that the sequence of Galerkin solution converges to this unique solution in mean square.

math.PR↗

arXiv2012

Existence and large time behaviour for a stochastic model of a modified magnetohydrodynamic equations

In this paper we initiate the mathematical analysis of a system of nonlinear Stochastic Partial Differential equations describing the motion of turbulent Non-Newtonian media in the presence of fluctuating magnetic field. The system is basically obtained by a coupling of the dynamical equations of a Non-Newtonian fluids having $p$-structure and the Maxwell equations. We mainly show the existence of weak martingale solutions and their exponential decay when time goes to infinity.

math.AP↗

arXiv2012

Controllability and Qualitative properties of the solutions to SPDEs driven by boundary Lévy noise

Let $u$ be the solution to the following stochastic evolution equation (1) du(t,x)& = &A u(t,x) dt + B σ(u(t,x)) dL(t),\quad t>0; u(0,x) = x taking values in an Hilbert space $\HH$, where $L$ is a $\RR$ valued Lévy process, $A:H\to H$ an infinitesimal generator of a strongly continuous semigroup, $σ:H\to \RR$ bounded from below and Lipschitz continuous, and $B:\RR\to H$ a possible unbounded operator. A typical example of such an equation is a stochastic Partial differential equation with boundary Lévy noise. Let $\CP=(\CP_t)_{t\ge 0}$ %{\CP_t:0\le t<\infty}$ the corresponding Markovian semigroup. We show that, if the system (2) du(t) = A u(t)\: dt + B v(t),\quad t>0 u(0) = x is approximate controllable in time $T>0$, then under some additional conditions on $B$ and $A$, for any $x\in H$ the probability measure $\CP_T^\star δ_x$ is positive on open sets of $H$. Secondly, as an application, we investigate under which condition on %$\HH$ and on the Lévy process $L$ and on the operator $A$ and $B$ the solution of Equation [1] is asymptotically strong Feller, respective, has a unique invariant measure. We apply these results to the damped wave equation driven by Lévy boundary noise.

math.PR↗

arXiv2012

Trajectory attractor for a non-autonomous Magnetohydrodynamic equations of Non-Newtonian Fluids

In this article we initiate the mathematical study of the dynamics of a system of nonlinear Partial Differential Equations modelling the motion of incompressible, isothermal and conducting modified bipolar fluids in presence of magnetic field. We mainly prove the existence of weak solutions to the model. We also prove the existence of a trajectory attractor to the translation semigroup acting on the trajectories of the set of weak solutions and that of external forces. Some results concerning the structure of this trajectory attractor are also given. The results from this paper may be useful in the investigation of some system of PDEs arising from the coupling of incompressible fluids of $p$-structure and the Maxwell equations.

math.AP↗