Simulation of Two-Dimensional Steady State Boundary Layers Applied to Nonideal Gas Flows (original) (raw)
Related papers
2011
Integral calculations of two-dimensional, incompressible, thermal, transitional boundary layers have been performed. To precede these approximate calculations, mathematical model was developed in order to enable prediction of the main boundary layer integral parameters. The model was proposed to calculate the characteristics of the boundary layers under the effect of local heat transfer and moderate free-stream turbulence levels by enhancing established integral techniques in conjunction with intermittency weighted model of the transitional boundary layer. Empirical relationships for the prediction of the start and end of transition, as well as the development of the boundary layer during the transition region were based on results of experimental investigations. Since the heat transfer coefficient between external flow and surface is extremely influenced by the level of turbulence in the flow, it is also found to be very sensitive to the solid surface temperature and thereby an ade...
AN INVESTIGATION OF THE OSEEN DIFFERENTIAL EQUATIONS FOR THE BOUNDARY LAYER
University of Salford, 2018
The thesis is on an investigation of the Oseen partial differential equations for the problem of laminar boundary layer flow for the steady two-dimensional case of an incompressible, viscous fluid with the boundary conditions that the velocity at the surface is zero and outside the boundary layer is the free stream velocity. It first shores-up some of the theory on using the Wiener-Hopf technique to determine the solution of the integral equation of Oseen flow past a semi-infinite flat plate. The procedure is introduced and it divides into two steps; first is to transform the Oseen equation (Oseen 1927) into an integral equation given by (Olmstead 1965), using the drag Oseenlet formula. Second is the solution of this integral equation by using the Wiener-Hopf technique (Noble 1958). Next, the Imai approximation (Imai 1951) is applied to the drag Oseenlet in the Oseen boundary layer representation, to show it approximates to Burgers solution (Burgers 1930). Additionally, a thin body theory is applied for the potential flow. This solution is just the same as the first linearization in Kusukawa’s solution (Kusukawa, Suwa et al. 2014) which, by applying successive Oseen linearization approximations, tends towards the Blasius/Howarth boundary layer (Blasius, 1908; Howarth, 1938). Moreover, comparisons are made with all the methods by developing a finite-difference boundary layer scheme for different Reynolds number and grid size in a rectangular domain. Finally, the behaviour of Stokes flow near field on the boundary layer is studied and it is found that by assuming a far-boundary layer Oseen flow matched to a near-boundary layer Stokes flow a solution is possible that is almost identical to the Blasius solution without the requirement for successive linearization. PhD thesis, University of Salford
Numerical Boundary Layer Theory With Case Studies
CFD Open Series, 2022
The concept of the boundary layer was developed by [Prandtl] in 1904. It provides an important link between ideal fluid flow and real-fluid flow. Fluids having relatively small viscosity , the effect of internal friction in a fluid is appreciable only in a narrow region surrounding the fluid boundaries. Since the fluid at the boundaries has zero velocity, there is a steep velocity gradient from the boundary into the flow. This velocity gradient in a real fluid sets up shear forces near the boundary that reduce the flow speed to that of the boundary. That fluid layer which has had its velocity affected by the boundary shear is called the boundary layer. For smooth upstream boundaries the boundary layer starts out as a laminar boundary layer in which the fluid particles move in smooth layers. As the laminar boundary layer increases in thickness, it becomes unstable and finally transforms into a turbulent boundary layer in which the fluid particles move in haphazard paths. When the boundary layer has become turbulent, there is still a very than layer next to the boundary layer that has laminar motion. It is called the laminar sub layer. Various definitions of boundary–layer thickness δ have been suggested. The most basic definition refers to the displacement of the main flow due to slowing down of particles in the boundary zone.
ADVANCED STUDY CASES FOR NUMERICAL ANALYSIS FACULTY POSTER ABSTRACT
A course on Numerical Methods typically covers introductory topics in numerical analysis for students of engineering, science, mathematics, and computer science who have completed elementary calculus, linear algebra and matrix theory. The course is usually limited to exploring basic algorithms for solving traditional simple problems in sciences and engineering . As a result, the students have become inadequately prepared to construct and explore more sophisticated algorithms of modern technological challenges. To reduce this gap, the author has offered a series of study cases, which provide concrete examples of the ways numerical methods lead to solutions of some scientific problems. The similar approach was promoted in [2].
Numerical Solution of 2D and 3D Atmospheric Boundary Layer Stratified Flows
Springer Proceedings in Mathematics, 2011
The work deals with the numerical solution of the 2D and 3D turbulent stratified flows in atmospheric boundary layer over the "sinus hills". Mathematical model for the turbulent stratified flows in atmospheric boundary layer is the Boussinesq model -Reynolds averaged Navier-Stokes equations (RANS) for incompressible turbulent flows with addition of the density change equation. The artificial compressibility method and the finite volume method have been used in all computed steady cases. Lax-Wendroff scheme (MacCormack form) has been used to find the numerical solution and turbulence was modeled by the Cebecci-Smith algebraic turbulence model. Computations have been performed with Reynold's number 10 8 that corresponds approximatelly to the upstream velocity u ∞ = 1.5 m s and with density range ρ ∈ [1.2; 1.1] kg m 3 .
Aspects of Boundary Layer Theory by David Weyburne ISBN
2021
This book is a review of several theoretical and experimental results dealing with boundary layers formed by fluid moving along a wall. It is not an exhaustive examination of boundary layer theory but instead is a summary of the work the author conducted while working as a civilian researcher at the United States Air Force Research Laboratory. The work primarily deals with the basic theory and conceptual models for boundary layer flow. Be forewarned that this is not a simple review of boundary layer theory found in the literature. Much of the work is a direct challenge to the basic theory and conceptual models existing in the present-day boundary layer literature. Most of the challenges come in a manner that is relatively easy for the reader to verify themselves. To further encourage the reader to verify the enclosed work, an Appendix is added to take the reader through the process of setting up and doing their own fluid flow simulations.
Aspects of Boundary Layer Theory
June, 2022
This updated book is a review of several theoretical and experimental results dealing with boundary layers formed by fluid moving along a wall. Topics include a new boundary layer velocity peaking model for mass and momentum conservation, a new simple explanation of aerodynamic lift using the peaking model, and a review of the integral moment method for describing boundary layer thickness and shape. Additional topics cover a range of boundary layer and turbulent boundary layer modeling. This version has one major update and some minor corrections to the previous version.