Third-order upwind finite element computation of the incompressible Navier-Stokes equations Part II. Aerodynamic characteristics of a rectangular cylinder with an angle of attack

1995 ◽  
Vol 127 (1-4) ◽  
pp. 99-113 ◽  
Author(s):  
Norio Kondo ◽  
Seija Yamada
2019 ◽  
pp. 4-17
Author(s):  
Олександр Миколайович Шийко ◽  
Анатолій Михайлович Павлюченко ◽  
Андрій Вікторович Скорик ◽  
Олексій Анатолійович Обухов ◽  
Ігор Володимирович Коплик

The subject of research in the article is the aerodynamic forces arising from the flight of supersonic feathered rotation bodies such as unguided rockets. The aim of the work is to develop a method for calculating the aerodynamic coefficients of the resultant forces and moments of supersonic feathered bodies of revolution such as unguided missiles when flown around at an angle of attack with pre-, trans- and supersonic speeds according to drawings of their external contours. Tasks: using modern software systems and flight experiments, develop a method for calculating the distribution of normal and tangential stresses over the surface of a supersonic feathered body of rotation, their equivalent and aerodynamic coefficients at up-, trans- and supersonic flow velocities at an angle of attack. The applied methods are the numerical solution of the Navier-Stokes equations, the use of two-parameter differential models of near-wall turbulent viscosity, verification of the methodology by comparing the results of calculations with the data of flight experiments and known data on the aerodynamic resistance of the object of research. The following results were obtained. Based on the numerical solution of the Navier-Stokes equations in the ANSYS CFX software package using the γ-ReΘt SST–model of Menter’s near-wall turbulence, a method is developed for calculating the aerodynamic characteristics of supersonic axially symmetric rotation bodies of uncontrollable missiles according to drawings of the external contours in the presence of a counter-flow angle. Using the developed technique it is possible to calculate the aerodynamic coefficients of friction resistance, pressure resistance and bottom resistance at sub-, trans- and supersonic speeds. Characteristics include the coefficients of the longitudinal aerodynamic force, transverse aerodynamic force, aerodynamic stabilizing moment and the coordinate of the center of pressure of the feathered body of rotation. For the calculations, were applied the external contours of the unguided missile M–21OФ. Calculations were performed for the counter-flow Mach numbers within0,1 £ M∞ £ 2,5. The aerodynamic coefficients were calculated as functions of the Mach number M∞. In order to determine the Reynolds number of the beginning of the laminar-turbulent transition in the boundary layer for this type of aircraft the characteristics of the friction resistance were calculated and compared with the flight data for two samples of research aerophysical complexes. Conclusions. The scientific novelty of the results is as follows: a pilot test was created and involved the results of flight experiments on Reynolds numbers of the start of a laminar-turbulent transition in the boundary layers of a method for calculating the aerodynamic drag coefficients of supersonic axially rotated bodies of rotation like uncontrollable missiles according to the drawings of their external contours during turning angle of attack based on the numerical solution of the Reynolds-averaged Navier-Stokes equations in the framework of the programme product ANSYS CFX using γ-ReΘt SST–Menter turbulence model. Verification of the calculation results was carried out on the basis of their comparison with the known values of the aerodynamic characteristics of the object of research with the axisymmetric flow.


Author(s):  
Alexander Danilov ◽  
Alexander Lozovskiy ◽  
Maxim Olshanskii ◽  
Yuri Vassilevski

AbstractThe paper introduces a finite element method for the Navier-Stokes equations of incompressible viscous fluid in a time-dependent domain. The method is based on a quasi-Lagrangian formulation of the problem and handling the geometry in a time-explicit way. We prove that numerical solution satisfies a discrete analogue of the fundamental energy estimate. This stability estimate does not require a CFL time-step restriction. The method is further applied to simulation of a flow in a model of the left ventricle of a human heart, where the ventricle wall dynamics is reconstructed from a sequence of contrast enhanced Computed Tomography images.


Author(s):  
Kangrui Zhou ◽  
Yueqiang Shang

AbstractBased on full domain partition, three parallel iterative finite-element algorithms are proposed and analyzed for the Navier–Stokes equations with nonlinear slip boundary conditions. Since the nonlinear slip boundary conditions include the subdifferential property, the variational formulation of these equations is variational inequalities of the second kind. In these parallel algorithms, each subproblem is defined on a global composite mesh that is fine with size h on its subdomain and coarse with size H (H ≫ h) far away from the subdomain, and then we can solve it in parallel with other subproblems by using an existing sequential solver without extensive recoding. All of the subproblems are nonlinear and are independently solved by three kinds of iterative methods. Compared with the corresponding serial iterative finite-element algorithms, the parallel algorithms proposed in this paper can yield an approximate solution with a comparable accuracy and a substantial decrease in computational time. Contributions of this paper are as follows: (1) new parallel algorithms based on full domain partition are proposed for the Navier–Stokes equations with nonlinear slip boundary conditions; (2) nonlinear iterative methods are studied in the parallel algorithms; (3) new theoretical results about the stability, convergence and error estimates of the developed algorithms are obtained; (4) some numerical results are given to illustrate the promise of the developed algorithms.


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