DSpace Collection:http://dspace.mediu.edu.my:8181/xmlui/handle/123456789/43272021-01-18T12:43:06Z2021-01-18T12:43:06ZStatic pressure and wall shear stress distributions in air flow in a seven wire-wrapped rod bundlehttp://dspace.mediu.edu.my:8181/xmlui/handle/123456789/46512013-05-30T11:30:52Z2013-05-30T00:00:00ZTitle: Static pressure and wall shear stress distributions in air flow in a seven wire-wrapped rod bundle
Description: An experimental investigation is performed in a turbulent flow in a seven wire-wrapped rod bundle, mounted in an open air facility. Static pressure distributions are measured on central and peripheral rods. By using a Preston tube, the wall shear stress profiles are experimentally obtained along the perimeter of the rods. The geometric parameters of the test section are P/D=1.20 and H/D=15. The measuring section is located at L/D=40 from the air inlet. It is observed that the dimensionless static pressure and wall shear stress profiles are nearly independent of the Reynolds number and strongly dependent of the wire-spacer position, with abrupt variations of the parameters in the neighborhood of the wires.2013-05-30T00:00:00ZContact with friction using the augmented Lagrangian Method: a conditional constrained minimization problemhttp://dspace.mediu.edu.my:8181/xmlui/handle/123456789/46452013-05-30T11:30:22Z2013-05-30T00:00:00ZTitle: Contact with friction using the augmented Lagrangian Method: a conditional constrained minimization problem
Description: This work presents a formulation of the contact with friction between elastic bodies. This is a non linear problem due to unilateral constraints (inter-penetration of bodies) and friction. The solution of this problem can be found using optimization concepts, modelling the problem as a constrained minimization problem. The Finite Element Method is used to construct approximation spaces. The minimization problem has the total potential energy of the elastic bodies as the objective function, the non-inter-penetration conditions are represented by inequality constraints, and equality constraints are used to deal with the friction. Due to the presence of two friction conditions (stick and slip), specific equality constraints are present or not according to the current condition. Since the Coulomb friction condition depends on the normal and tangential contact stresses related to the constraints of the problem, it is devised a conditional dependent constrained minimization problem. An Augmented Lagrangian Method for constrained minimization is employed to solve this problem. This method, when applied to a contact problem, presents Lagrange Multipliers which have the physical meaning of contact forces. This fact allows to check the friction condition at each iteration. These concepts make possible to devise a computational scheme which lead to good numerical results.2013-05-30T00:00:00ZAlgorithm to determine the intersection curves between bezier surfaces by the solution of multivariable polynomial system and the differential marching methodhttp://dspace.mediu.edu.my:8181/xmlui/handle/123456789/46392013-05-30T11:29:52Z2013-05-30T00:00:00ZTitle: Algorithm to determine the intersection curves between bezier surfaces by the solution of multivariable polynomial system and the differential marching method
Description: The determination of the intersection curve between Bézier Surfaces may be seen as the composition of two separated problems: determining initial points and tracing the intersection curve from these points. The Bézier Surface is represented by a parametric function (polynomial with two variables) that maps a point in the tridimensional space from the bidimensional parametric space. In this article, it is proposed an algorithm to determine the initial points of the intersection curve of Bézier Surfaces, based on the solution of polynomial systems with the Projected Polyhedral Method, followed by a method for tracing the intersection curves (Marching Method with differential equations). In order to allow the use of the Projected Polyhedral Method, the equations of the system must be represented in terms of the Bernstein basis, and towards this goal it is proposed a robust and reliable algorithm to exactly transform a multivariable polynomial in terms of power basis to a polynomial written in terms of Bernstein basis .2013-05-30T00:00:00ZAn alternative finite element formulation for determination of streamlines in two-dimensional problemshttp://dspace.mediu.edu.my:8181/xmlui/handle/123456789/46332013-05-30T11:29:22Z2013-05-30T00:00:00ZTitle: An alternative finite element formulation for determination of streamlines in two-dimensional problems
Description: It is well known that the numerical solutions of incompressible viscous flows are of great importance in Fluid Dynamics. The graphics output capabilities of their computational codes have revolutionized the communication of ideas to the non-specialist public. In general those codes include, in their hydrodynamic features, the visualization of flow streamlines - essentially a form of contour plot showing the line patterns of the flow - and the magnitudes and orientations of their velocity vectors. However, the standard finite element formulation to compute streamlines suffers from the disadvantage of requiring the determination of boundary integrals, leading to cumbersome implementations at the construction of the finite element code. In this article, we introduce an efficient way - via an alternative variational formulation - to determine the streamlines for fluid flows, which does not need the computation of contour integrals. In order to illustrate the good performance of the alternative formulation proposed, we capture the streamlines of three viscous models: Stokes, Navier-Stokes and Viscoelastic flows.2013-05-30T00:00:00Z