arXiv subjects

Nianzheng Cao

Publications and source records attributed to Nianzheng Cao.

4 recordsLinked to original sources

arXiv1997

Anomalous Scaling and Structure Instability in Three-Dimensional Passive Scalar Turbulence

The anomalous scaling phenomena of three-dimensional passive scalar turbulence are studied using high resolution direct numerical simulation. The inertial range scaling exponents of the passive scalar increment and the scalar dissipation are obtained. The connection between the intermittency structure and the scaling exponent is examined and the structure instability of the high amplitude scalar dissipation is used to clarify previous experimental results for the scaling exponents.

chao-dyn↗

arXiv1997

An Intermittency Model For Passive-Scalar Turbulence

A phenomenological model for the inertial range scaling of passive-scalar turbulence is developed based on a bivariate log-Poisson model. An analytical formula of the scaling exponent for three-dimensional passive-scalar turbulence is deduced. The predicted scaling exponents are compared with experimental measurements, showing good agreement.

chao-dyn↗

arXiv1997

A Refined Similarity Hypothesis for Transverse Structure Functions

We argue on the basis of empirical data that Kolmogorov's refined similarity hypothesis (RSH) needs to be modified for transverse velocity increments, and propose an alternative. In this new form, transverse velocity increments bear the same relation to locally averaged enstrophy (squared vorticity) as longitudinal velocity increments bear in RSH to locally averaged dissipation. We support this hypothesis by analyzing high-resolution numerical simulation data for isotropic turbulence. RSH and its proposed modification for transverse velocity increments (RSHT) appear to represent two independent scaling groups.

chao-dyn↗

arXiv1996

Scaling of Low-Order Structure Functions in Homogeneous Turbulence

High-resolution direct numerical simulation data for three-dimensional Navier-Stokes turbulence in a periodic box are used to study the scaling behavior of low-order velocity structure functions with positive and negative powers. Similar to high-order statistics, the low-order relative scaling exponents exhibit unambiguous departures from the Kolmogorov 1941 theory and agree well with existing multiscaling models. No transition from normal scaling to anomalous scaling is observed.

chao-dyn↗