Teaching Documents by Ideen Sadrehaghighi
CFD Open Series, 2023
Numerical calculations on four blade passages are done using Q3D Navier-Stokes solver with a simp... more Numerical calculations on four blade passages are done using Q3D Navier-Stokes solver with a simple mixing length turbulence model and two more advanced transport-equation approaches. Mixing length is simple and cheap but crude, while more sophisticated transport approaches are more physical but more expensive. Predicted results using different turbulent models are discussed and compared with the laminar flow and well documented experimental results. Studies show that the model with more transport-equation predicts improved result as it includes the effects of upstream history into the velocity scale.
CFD Open Series, 2022
In the adaptive mesh refinement technique we start with a base coarse grid. As the solution proce... more In the adaptive mesh refinement technique we start with a base coarse grid. As the solution proceeds we identify the regions requiring more resolution by some parameter characterizing the solution, say the local truncation error. We superimpose finer sub grids only on these regions. Finer and finer sub grids are added recursively until either a given maximum level of refinement is reached or the local truncation error has dropped below the desired level. Thus in an adaptive mesh refinement computation grid spacing is fixed for the base grid only and is determined locally for the sub grids according to the requirements of the problem
CFD Open Series, 2022
The immersed boundaries (IB) method allows one to greatly simplify the grid generation and even t... more The immersed boundaries (IB) method allows one to greatly simplify the grid generation and even to automate it completely. The governing equations are solved directly on a grid in their simplest form by means of very efficient numerical schemes. The grid generator detects the cell faces that are cut by the body surface and divides the cells into three types: solid and fluid cells, whose centers lie within the body and within the fluid, respectively; and fluid/solid interface cells, which have at least one of their neighbors inside the body/fluid. Then, the centers of the fluid and solid-interface cells are projected onto the body surface along its normal direction, so as to obtain fluid-cells projection points and solid-cell projection points.
CFD Open Series, 2022
Lattice Boltzmann Methods (LBM) or Thermal Lattice Boltzmann Methods (TLBM) is a CFD methods for ... more Lattice Boltzmann Methods (LBM) or Thermal Lattice Boltzmann Methods (TLBM) is a CFD methods for fluid simulation. Instead of solving the Navier–Stokes equations, the discrete Boltzmann equation is solved to simulate the flow of a Newtonian fluid with collision models such as Bhatnagar–Gross–Krook (BGK). By simulating streaming and collision processes across a limited number of particles, the intrinsic particle interactions evince a microcosm of viscous flow behavior applicable across the greater mass1. It is a modern approach in Computational Fluid Dynamics and often used to solve the incompressible, time-dependent Navier-Stokes equations numerically. Its strength lies however in the ability to easily represent complex physical phenomena, ranging from multiphase flows to chemical interactions between the fluid and the surroundings.
CFD Open Series, 2022
In mathematics and computer science, an optimization problem is the problem of finding the best s... more In mathematics and computer science, an optimization problem is the problem of finding the best solution from all feasible solutions. In the simplest terms, an optimization problem consists of maximizing or minimizing a real function by systematically choosing input values from within an allowed set and computing the value of the function.
CFD Open Series, 2023
This note is intended for all undergraduate, graduate, and scholars of Turbomachinery. It is not ... more This note is intended for all undergraduate, graduate, and scholars of Turbomachinery. It is not completed and never claims to be as such. Therefore, all the comments are greatly appreciated. In assembling that, I was influenced with sources from my textbooks, papers, and materials that I deemed to be important. At best, it could be used as a reference. I also would like to express my appreciation to several people who have given thoughts and time to the development of this article. Special thanks should be forwarded to the authors whose papers seemed relevant to topics, and consequently, it appears here ©. Finally I would like to thank my wife, Sudabeh for her understanding and the hours she relinquished to me. Their continuous support and encouragement are greatly appreciated.
CFD Open Series, 2022
Multigrid methods are effective techniques that can deliver fast convergence rates with minimal m... more Multigrid methods are effective techniques that can deliver fast convergence rates with minimal memory overheads. The basic idea of a multigrid method is to accelerate the solution of a set of fine grid equations by time stepping on a sequence of fine and coarse grids using a simple explicit scheme.
CFD Open Series, 2022
Anisotropic meshes are desirable for various applications, such as the numerical solving of parti... more Anisotropic meshes are desirable for various applications, such as the numerical solving of partial differential equations and graphics. From an equivalent point of view, the use of meshes whose elements are stretched according to the anisotropy requires a lower number of elements to achieve the same precision of the result of the simulation. When stretched elements are used, the mesh is said to be Anisotropic. Additionally to providing increased accuracy in the simulations of scientific modeling, anisotropic meshes also find use in geometric modeling as they can improve the visualization of objects, and lower the number of vertices required to represent a shape or interpolate a smooth function. By requiring fewer elements, anisotropic meshes thus provide another way to accelerate mesh generation, and increase the quality and the speed of computations.
CFD Open Series, 2022
Computer-Aided Design (CAD) is the use of computer systems (or workstations) to aid in the creati... more Computer-Aided Design (CAD) is the use of computer systems (or workstations) to aid in the creation, modification, analysis, or optimization of a design. CAD software is used to increase the productivity of the designer, improve the quality of design, improve communications through documentation, and to create a database for manufacturing. CAD output is often in the form of electronic files for print, machining, or other manufacturing operations. The term CADD (for Computer Aided Design and Drafting) is also used. CAD may be used to design curves and figures in two-dimensional (2D) space; or curves, surfaces, and solids in three-dimensional (3D) space. CAD is an important industrial art extensively used in many applications, including automotive, shipbuilding, and aerospace industries, industrial and architectural design, prosthetics, and many more. CAD is also widely used to produce computer animation for special effects in movies, advertising and technical manuals, often called DCC digital content creation. The modern ubiquity and power of computers means that even perfume bottles and shampoo dispensers are designed using techniques unheard of by engineers of the 1960s. Because of its enormous economic importance, CAD has been a major driving force for research in computational geometry, computer graphics (both hardware and software), and discrete differential geometry.
CFD OpenSeries, 2023
A Mach 0.93 Blended-Wing-Body (BWB) configuration was developed using CFL3DV6, a Navier-Stokes co... more A Mach 0.93 Blended-Wing-Body (BWB) configuration was developed using CFL3DV6, a Navier-Stokes computational fluid dynamics (CFD) code, in conjunction with the Wing Multidisciplinary Optimization Design (WingMOD) code, to determine the feasibility of BWB aircraft at high subsonic speeds. Excluding an assessment of propulsion airframe interference, the results show that a Mach 0.93 BWB is feasible, although it pays a performance penalty relative to Mach 0.85 designs. A Mach 0.90 BWB may be the best solution in terms of offering improved speed with minimal performance penalty. 2.1.2 2.2 Case Study 2-Changing the Role of CFD in Aircraft Development
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Teaching Documents by Ideen Sadrehaghighi