Computational Methods for High Energy Physics

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Three-Dimensional Piezothermoelastic Stress of a Finite Functionally Graded Cylindrical Shell with Piezoelectric Layer

Three-dimensional piezothermoelastic solutions for a finite functionally graded cylindrical shell with piezoelectric layer are carried out in this paper. The cylindrical shell is simply supported at four end edges and is subjected to axisymmetric thermomechanical loads. The piezoelectric layers are polarized along radial direction as a sensor. The material properties are assumed to be temperature independent and radially dependent but are assumed to be homogeneous in each layer; the variables are expanded in Fourier series to satisfy the boundary conditions and multilayer approach is used. Numerical results of mullite/molybdenum functionally graded cylindrical shell are presented; the temperature change, stresses, electric potential, and electric displacement distributions are given and briefly discussed

Numerical and Experimental Investigation on the Flow Separation Control of S809 Airfoil with Slot

A new flow control approach called split blade is applied on the S809 airfoil in the present study. S809 airfoil was investigated experimentally and numerically with different operating conditions including cascade without control, cascade with slots that generate jets with AOAs of 0 degrees, 10 degrees, 15 degrees and 20 degrees. Good agreement was obtained between the comparison of the experimental and numerical results. The results show that the separation area increases with increase of the AOA and the large separation area appears on the airfoil suction surface at AOA equal to 20 degrees. Numerical results show that the control method has little negative influence on the airfoil performance at small AOAs. Smaller vortices are filled with the large separated area which is divided by the jet generated by split when the AOA is 20 degrees. The analysis on the lift coefficient and drag coefficient shows that the flow is improved with the control. The lift coefficient and drag coefficient do not change in the comparison between the cases before and after control when AOA is 0 degrees and 10 degrees. However, the lift coefficient increases and drag coefficient decreases when AOA is 15 degrees and 20 degrees

Energy Loss in Pulse Detonation Engine due to Fuel Viscosity

Fluid viscosity is a significant factor resulting in the energy loss in most fluid dynamical systems. To analyze the energy loss in the pulse detonation engine (PDE) due to the viscosity of the fuel, the energy loss in the Burgers model excited by periodic impulses is investigated based on the generalized multisymplectic method in this paper. Firstly, the single detonation energy is simplified as an impulse; thus the complex detonation process is simplified. And then, the symmetry of the Burgers model excited by periodic impulses is studied in the generalized multisymplectic framework and the energy loss expression is obtained. Finally, the energy loss in the Burgers model is investigated numerically. The results in this paper can be used to explain the difference between the theoretical performance and the experimental performance of the PDE partly. In addition, the analytical approach of this paper can be extended to the analysis of the energy loss in other fluid dynamic systems due to the fluid viscosity

Computational Analysis of Propulsion Performance of Modified Pitching Motion Airfoils in Laminar Flow

The thrust generation performance of airfoils with modified pitching motion was investigated by computational fluid dynamics (CFD) modeling two-dimensional laminar flow at Reynolds number of 104. The effect of shift distance of the pitch axis outside the chord line (R), reduced frequency (k), pitching amplitude (θ), pitching profile, and airfoil shape (airfoil thickness and camber) on the thrust generated and efficiency were studied. The results reveal that the increase in R and k leads to an enhancement in thrust generation and a decrease in propulsive efficiency. Besides, there exists an optimal range of θ for the maximum thrust and the increasing θ induces a rapid decrease in propulsive efficiency. Six adjustable parameters (K) were employed to realize various nonsinusoidal pitching profiles. An increase in K results in more thrust generated at the cost of decreased propulsive efficiency. The investigation of the airfoil shape effect reveals that there exists an optimal range of airfoil thickness for the best propulsion performance and that the vortex structure is strongly influenced by the airfoil thickness, while varying the camber or camber location of airfoil sections offers no benefit in thrust generation over symmetric airfoil sections

An Analytical Solution for Acoustic Emission Source Location for Known P Wave Velocity System

This paper presents a three-dimensional analytical solution for acoustic emission source location using time difference of arrival (TDOA) measurements from N receivers, N⩾5. The nonlinear location equations for TDOA are simplified to linear equations, and the direct analytical solution is obtained by solving the linear equations. There are not calculations of square roots in solution equations. The method solved the problems of the existence and multiplicity of solutions induced by the calculations of square roots in existed close-form methods. Simulations are included to study the algorithms' performance and compare with the existing technique

A parallel algorithm of ICSYM for complex symmetric linear systems in quantum chemistry

Computational effort is a common issue for solving large-scale complex symmetric linear systems, particularly in quantum chemistry applications. In order to alleviate this problem, we propose a parallel algorithm of improved conjugate gradient-type iterative (CSYM). Using three-term recurrence relation and orthogonal properties of residual vectors to replace the tridiagonalization process of classical CSYM, which allows to decrease the degree of the reduce-operator from two to one communication at each iteration and to reduce the amount of vector updates and vector multiplications. Several numerical examples are implemented to show that high performance of proposed improved version is obtained both in convergent rate and in parallel efficiency

Predictor-Corrector LU-SGS Discontinuous Galerkin Finite Element Method for Conservation Laws

Efficient implicit predictor-corrector LU-SGS discontinuous Galerkin (DG) approach for compressible Euler equations on unstructured grids is investigated by adding the error compensation of high-order term. The original LU-SGS and GMRES schemes for DG method are discussed. Van Albada limiter is employed to make the scheme monotone. The numerical experiments performed for the transonic inviscid flows around NACA0012 airfoil, RAE2822 airfoil, and ONERA M6 wing indicate that the present algorithm has the advantages of low storage requirements and high convergence acceleration. The computational efficiency is close to that of GMRES scheme, nearly 2.1 times greater than that of LU-SGS scheme on unstructured grids for 2D cases, and almost 5.5 times greater than that of RK4 on unstructured grids for 3D cases