# Stochastic phase field $\alpha$-Navier-Stokes vesicle-fluid interaction model

## TL;DR

This paper introduces a stochastic version of a coupled phase field and alpha-Navier-Stokes model to describe vesicle-fluid interactions, proving existence and uniqueness of solutions with additive noise.

## Contribution

It develops a stochastic perturbation framework for the vesicle-fluid interaction model and establishes well-posedness results for the resulting nonlinear PDE system.

## Key findings

- Existence and uniqueness of solutions in classical $L^{2}$ spaces.
- A priori estimates for nonlinear terms and bending energy.
- Methodology based on tightness and regularity of finite-dimensional approximations.

## Abstract

We consider a stochastic perturbation of the phase field alpha-Navier-Stokes model with vesicle-fluid interaction. It consists in a system of nonlinear evolution partial differential equations modeling the fluid-structure interaction associated to the dynamics of an elastic vesicle immersed in a moving incompressible viscous fluid. This system of equations couples a phase-field equation -- for the interface between the fluid and the vesicle -- to the alpha-Navier-Stokes equation -- for the viscous fluid -- with an extra nonlinear interaction term, namely the bending energy. The stochastic perturbation is an additive space-time noise of trace class on each equation of the system. We prove the existence and uniqueness of solution in classical spaces of $L^{2}$ functions with estimates of non-linear terms and bending energy. It is based on a priori estimate about the regularity of solutions of finite dimensional systems, and tightness of the approximated solution.