Coherent Structure Eduction in Wavelet-forced Two-dimensional Turbulent Flows
نویسندگان
چکیده
We analyze vorticity fields obtained from direct numerical simulations (DNS) of statistically stationary two-dimensional turbulence where the forcing is done in wavelet space. We introduce a new eduction method for extracting coherent structures from two-dimensional turbulent flows. Using a nonlinear wavelet technique based on an objective universal threshold we separate the vorticity field into coherent structures and background flow. Both components are multi-scale with different scaling laws, and therefore cannot be separated by Fourier filtering. We find that the coherent structures have non-Gaussian statistics while the background flow is Gaussian, and we discuss the implications of this result for turbulence modelling.
منابع مشابه
Identification of Coherent Structure in Turbulent Shear Flow With Wavelet Correlation
Hui Li Analysis Department of Mechanical Engineering, Faculty of Engineering, Kagoshima University, In order to identify coherent structure of turbulent shear flow, a new combination 1-21-40, Korimoto, of familiar techniques of signal processing, called wavelet correlation analysis, is Kagoshima City, Japan developed based on the wavelet transform. The wavelet correlation analysis provides Mem....
متن کاملApplication of the Schwarz-Christoffel Transformation in Solving Two-Dimensional Turbulent Flows in Complex Geometries
In this paper, two-dimensional turbulent flows in different and complex geometries are simulated by using an accurate grid generation method. In order to analyze the fluid flow, numerical solution of the continuity and Navier-Stokes equations are solved using CFD techniques. Considering the complexity of the physical geometry, conformal mapping is used to generate an orthogonal grid by means of...
متن کاملStochastic Coherent Adaptive Large Eddy Simulation Method
In this paper we propose a novel approach called the stochastic coherent adaptive large eddy simulation ~SCALES! method which takes advantage of both the coherent vortex simulation ~CVS! and large eddy simulation ~LES! methods. With the SCALES method a wavelet filter is applied to a turbulent field such that the maximum number of modes are resolved in the simulation, given the balance between c...
متن کاملOn Coherent Structures of Turbulent Open-channel Flow Above a Rough Bed
Present study examines turbulent structures of a rough bed open-channel flow in the context of deterministic approach. Instantaneous velocity field is measured in different hydraulic conditions using two dimensional Particle Image Velocimetry (PIV) in vertical plane and Stereoscopic PIV in horizontal plane. Different techniques and quantities such as swirl strength, two-point and cross-correlat...
متن کاملVisualization of Coherent Structures in Acoustically Forced, Gas-Particle Turbulent Round Jet
To show the effects of the particles and forced disturbances on the instantaneous large-scale vortex structures in a gas-particle round jet, coherent structures in gas-particle turbulent round jets were investigated experimentally by flow visualization. The 45m and 350m diameter glass beads were used as the particles in the experiments. An acoustic speaker was used to introduce velocity perturb...
متن کامل