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Cheng Yu

Publications and source records attributed to Cheng Yu.

89 records · Page 5Linked to original sources
arXiv2018

Onsager's energy conservation for inhomogeneous Euler equations

This paper addresses the problem of energy conservation for the two- and three-dimensional density-dependent Euler equations. Two types of sufficient conditions on the regularity of solutions are provided to ensure the conservation of total kinetic energy on the entire time interval including the initial time. The first class of data assumes integrability on the spatial gradient of the density, and hence covers the classical result of Constantin-E-Titi for the homogeneous Euler equations. The other type of data imposes extra time Besov regularity on the velocity profile, and the corresponding result can be applied to deal with a wide class of rough density profiles.

math.AP↗
arXiv2018

Global weak solutions to compressible Navier-Stokes-Vlasov-Boltzmann systems for spray dynamics

This work concerns the global existence of the weak solutions to a system of partial differential equations modeling the evolution of particles in the fluid. That system is given by a coupling between the standard isentropic compressible Navier-Stokes equations for the macroscopic description of a gas fluid flow, and a Vlasov-Boltzmann type equation governing the evolution of spray droplets modeled as particles with varying radius. We establish the existence of global weak solutions with finite energy, whose density of gas satisfies the renormalized mass equation. The proof, is partially motivated by the work of Feireisl- Novotny-Petzeltov on the weak solutions of the compressible Navier-Stokes equations coupled to the kinetic problem for the spray droplets extending the techniques of Legger and Vasseur developed for the incompressible fluid-kinetic system.

math.AP↗
arXiv2017

Existence of global weak solutions for the Navier-Stokes-Vlasov-Boltzmann equations

A moderately thick spray can be described by a coupled system of equations consisting of the incompressible Navier-Stokes equations and the Vlasov-Boltzmann equation. We investigate this kind of mathematical model in this paper. In particular, we study the initial value problem for the Navier-Stokes-Vlasov-Boltzmann equations. The existence of global weak solutions is established by a weak convergence method. The interesting point of our main result is to handle the model with some breakup effects while the velocity of particles is in the whole space.

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arXiv2017

Global weak solution to the viscous two-fluid model with finite energy

In this paper, we prove the existence of global weak solutions to the compressible two-fluid Navier-Stokes equations in three dimensional space. The pressure depends on two different variables from the continuity equations. We develop an argument of variable reduction for the pressure law. This yields to the strong convergence of the densities, and provides the existence of global solutions in time, for the compressible two-fluid Navier-Stokes equations, with large data in three dimensional space.

math.AP↗
arXiv2017

Energy conservation for the weak solutions of the compressible Navier-Stokes equations

In this paper, we prove the energy conservation for the weak solutions of the compressible Navier-Stokes equations for any time $t>0$, under certain conditions. The results hold for the renormalized solutions of the equations with constant viscosities, as well as the weak solutions of the equations with degenerate viscosity. Our conditions do not depend on the dimensions. The energy may conserve on the vacuum for the compressible Navier-Stokes equations with constant viscosities. Our results are the first ones on the energy conservation for the weak solutions of the compressible Navier-Stokes equations.

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arXiv2016

The weak solution to a Boltzmann type equation and its energy conservation

In this paper, we study the initial value problem of a Boltzmann type equation with a nonlinear degenerate damping. We prove the existence of global weak solutions with large initial data, in three dimensional space. We rely on a variant version of the Gronwall inequality and $L^p$ regularity of average velocities to derive the compactness of solutions to a suitable approximation. This allows us to recover a weak solution by passing to the limits. After the existence result, we also prove energy conservation for the weak solution under some certain condition.

math.AP↗
arXiv2015

Global weak solutions to compressible quantum Navier-Stokes equations with damping

The global-in-time existence of weak solutions to the barotropic compressible quantum Navier-Stokes equations with damping is proved for large data in three dimensional space. The model consists of the compressible Navier-Stokes equations with degenerate viscosity, and a nonlinear third-order differential operator, with the quantum Bohm potential, and the damping terms. The global weak solutions to such system is shown by using the Faedo-Galerkin method and the compactness argument. This system is also a very important approximated system to the compressible Navier-Stokes equations. It will help us to prove the existence of global weak solutions to the compressible Navier-Stokes equations with degenerate viscosity in three dimensional space.

math.AP↗
arXiv2015

Existence of Global Weak Solutions for 3D Degenerate Compressible Navier-Stokes Equations

In this paper, we prove the existence of global weak solutions for 3D compressible Navier-Stokes equations with degenerate viscosity. The method is based on the Bresch and Desjardins entropy conservation. The main contribution of this paper is to derive the Mellet-Vasseur type inequality for the weak solutions, even if it is not verified by the first level of approximation. This provides existence of global solutions in time, for the compressible Navier-Stokes equations, for any $γ>1$, in three dimensional space, with large initial data possibly vanishing on the vacuum. This solves an open problem proposed by Lions.

math.AP↗
arXiv2013

Almost sure existence of Navier-Stokes Equations with randomized data in the whole space

This paper considers the supercritical Navier-Stokes equations posed in the whole space $\R^d$, with suitably randomized initial data, in the weak solution setting. The global weak solutions are constructed for a large set of initial data in $H^{-s}(\R^d)$ for some $s>0$ via a probabilistic argument, and this in turn implies the almost sure existence.

math.AP↗
arXiv2013

Global weak solution for a coupled compressible Navier-Stokes and Q-tensor system

In this paper, we study a coupled compressible Navier-Stokes/Q-tensor system modeling the nematic liquid crystal flow in a three-dimensional bounded spatial domain. The existence and long time dynamics of globally defined weak solutions for the coupled system are established, using weak convergence methods, compactness and interpolation arguments. The symmetry and traceless properties of the Q-tensor play key roles in this process.

math.AP↗
arXiv2013

Global weak solutions to the inhomogeneous Navier-Stokes-Vlasov equations

A fluid-particle system of the inhomogeneous Navier-Stokes equations and Vlasov equation in the three dimensional space is considered in this paper. The coupling arises from the drag force in the fluid equations and the acceleration in the Vlasov equation. An initial-boundary value problem is studied in a bounded domain with large data. The existence of global weak solutions is established through an approximation scheme, energy estimates, and weak convergence.

math.AP↗
arXiv2012

Global weak solutions to the Navier-Stokes-Vlasov equations

In this paper, the system of particles coupled with fluid is considered. The particles are described by a Vlasov equation, and the fluid is governed by a forced Navier-Stokes equations. The interaction with fluid phase governed by Navier-Stokes equations is taken into account through a source term. The resulting system, namely Navier-Stokes-Vlasov equations, is shown to have global weak solutions in three spatial dimensions, and to have a unique global solution in two spatial dimensions.

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arXiv2011

Incompressible limit for the compressible flow of liquid crystals

The connection between the compressible flow of liquid crystals with low Mach number and the incompressible flow of liquid crystals is studied in a bounded domain. In particular, the convergence of weak solutions of the compressible flow of liquid crystals to the weak solutions of the incompressible flow of liquid crystals is proved when the Mach number approaches zero; that is, the incompressible limit is justified for weak solutions in a bounded domain.

math.AP↗
arXiv2011

Global weak solution and large-time behavior for the compressible flow of liquid crystals

The three-dimensional equations for the compressible flow of liquid crystals are considered. An initial-boundary value problem is studied in a bounded domain with large data. The existence and large-time behavior of a global weak solution are established through a three-level approximation, energy estimates, and weak convergence for the adiabatic exponent $γ>\frac32$.

math.AP↗