2013 1(12)

STUDY OF DIELECTRIC LIQUID STRUCTURE IN HIGH ELECTRIC FIELD WITH MOLECULAR DYNAMICS

Karpov D.I.

Lavrentyev Institute of Hydrodynamics SB RAS, Novosibirsk, Russia

Introduction

Study of electrohydrodynamic flows has both fundamental and practical interest (for example, for designing micro-dosage devices, electrohydrodynamic pumps and so on). The flows in the electrolyte in external electric field developed because of ion motions. The ion involves the part of liquid in motion. The flows developed in liquid dielectrics in external non-uniform electric field because of the action of electric forces on dipole molecules. The most appropriate method for studying microprocesses in liquid is the molecular dynamic method. There is only one work devoted to the study of the molecular dynamics of dielectric liquids under the action of extremely high electric field that lead to electrical breakdown of liquid. Therefore, from the practical and scientific term, this investigation is actual at present.  

Purpose

The purpose of the work is investigation of the dynamics of molecules of a polar dielectric liquid under the action of high electric fields with the molecular dynamic method for large ensembles of molecules.

Method

A method of molecular dynamics was realized taking into account the electric forces in dielectric liquids in a strong electric field. The Lennard-Jones potential was used for simulating the intermolecular interactions. The Coulomb potential was used for simulating electrical interactions. Dipoles were simulated by placing the pairs of charge of the opposite signs to the each molecule. A computer program was developed for parallel computing using graphic processor units by NVIDIA Corporation. The program allows accelerating the calculation from 40 to 50 times. The CUDA technology of programming was used.

Results

The calculations were performed of an anisotropic spinodal decomposition of a polar dielectric under the action of strong electric field for large ensembles of molecules. The formation of vapour channels oriented along the electric filed forces was simulated. This process is appeared to be similar to crack formation in solids. The region of influence of an ion in a liquid media on polar molecules of a dielectric was studied at various densities. The distributions of the electric field potential in dielectric media near the ion were calculated at various densities. The depth of the potential well decreases with the density. The results obtained are important for understanding the mechanisms of generation of hydrodynamic flows at electrical breakdown of liquid dielectrics.

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