Probability distribution functions in turbulent convection

Results of an extensive investigation of probability distribution functions (pdfs) for Rayleigh-Benard convection, in hard turbulence regime, are presented. It is shown that the pdfs exhibit a high degree of internal universality. In certain cases this universality is established within two Kolmogorov scales of a boundary. A discussion of the factors leading to the universality is presented

Problems in fluid dynamics

A scheme was developed for the parametric differentiation and integration of gas dynamics equations. A numerical integration of the gas dynamics equations is necessarily performed for a specific set of parameter values. The linear variational equations are obtained by differentiating the exact equations with respect to each of the relevant parameters. The resulting matrix of flow quantities is referred to as the Jacobi matrix. The subsequent procedure is then straightforward. The method was tested for two dimensional supersonic flow past an airfoil, with airfoil thickness, camber, and angle of attack varied. This approach has great potential value for rapidly assessing the effect of design changes. The other focus of the work was on problems in fluid stability, bifurcations, and turbulence

Approximate and exact numerical integration of the gas dynamic equations

A highly accurate approximation and a rapidly convergent numerical procedure are developed for two dimensional steady supersonic flow over an airfoil. Examples are given for a symmetric airfoil over a range of Mach numbers. Several interesting features are found in the calculation of the tail shock and the flow behind the airfoil

Mitigation of Cyclonic Activity

Under realistic estimates of geophysical conditions, two procedures are presented for diminishing the intensity of a hurricane: before it reaches landfall; or quenching it in its incipient stage. We demonstrate that within present-day technology, it is possible to mix the cold deep ocean with the warm surface layer sufficiently, and in a timely manner, in order to decrease the intensity. Two strategies will be presented: (1) In a manner similar to hurricane weakening by landfall, a virtual early landfall is created on the hurricane path, before true landfall; (2) The ocean surface area of an identified tropical depression or storm, with hurricane potential, is tracked and cooled by continued anti-cyclonic mixing until it is no longer a threat. Estimates of the power needed to perform the needed ocean mixing, in a timely manner, shows that this might be accomplished by assembling a sufficient number of high performance submarines. Accomplishment is facilitated by a remarkably high coefficient of performance, O(10^4). Destructive power ~Vm^3 , where Vm is maximal hurricane wind speed, thus even a modest 20% reduction in wind speed produces a ~50% reduction in damage causality. Novel submarine modifications are introduced to achieve the mixing process It is the contention of this paper that a practical framework exists for sensibly reducing the tragedy and devastation caused by hurricanes

A Modular Regularized Variational Multiscale Proper Orthogonal Decomposition for Incompressible Flows

In this paper, we propose, analyze and test a post-processing implementation of a projection-based variational multiscale (VMS) method with proper orthogonal decomposition (POD) for the incompressible Navier-Stokes equations. The projection-based VMS stabilization is added as a separate post-processing step to the standard POD approximation, and since the stabilization step is completely decoupled, the method can easily be incorporated into existing codes, and stabilization parameters can be tuned independent from the time evolution step. We present a theoretical analysis of the method, and give results for several numerical tests on benchmark problems which both illustrate the theory and show the proposed method's effectiveness

The Wigner Transform and Some Exact Properties of Linear Operators

The Wigner transform of an integral kernel on the full line generalizes the Fourier transform of a translation kernel. The eigenvalue spectra of Hermitian kernels are related to the topographic features of their Wigner transforms. Two kernels whose Wigner transforms are equivalent under the unimodular affine group have the same spectrum of eigenvalues and have eigenfunctions related by an explicit linear transformation. Any kernel whose Wigner transform has concentric ellipses as contour lines, yields an eigenvalue problem which may be solved exactly

Skin Segmentation based Elastic Bunch Graph Matching for efficient multiple Face Recognition

This paper is aimed at developing and combining different algorithms for face detection and face recognition to generate an efficient mechanism that can detect and recognize the facial regions of input image. For the detection of face from complex region, skin segmentation isolates the face-like regions in a complex image and following operations of morphology and template matching rejects false matches to extract facial region. For the recognition of the face, the image database is now converted into a database of facial segments. Hence, implementing the technique of Elastic Bunch Graph matching (EBGM) after skin segmentation generates Face Bunch Graphs that acutely represents the features of an individual face enhances the quality of the training set. This increases the matching probability significantly.Comment: 10 Pages Advances in Computer Science, Engineering Applications, May, 201