White Papers

Using Computational Fluid Dynamics (CFD) is no longer relegated to the realm of the specialist. A new class of CFD analysis software, ‘Concurrent CFD’, is proving to be highly effective at performing heat transfer analysis, enabling mechanical engineers to accelerate key decisions at their workstations and without the need for CFD specialists. Embedded into the MCAD environment, this intuitive process allows designers to optimize a product during the design stages reducing manufacturing costs across a wide range of mechanical designs and systems.

Research from Aberdeen's Q1 2011 business review has found that the top strategy for manufacturers, reported by 46%, is to improve business execution. What does this mean for new product development? A look at Aberdeen's October 2010 "NPD - the 2011 Growth Imperative: Optimizing Speed and Cost in New Product Development" report reveals the top challenges that must be addressed to accomplish this.

For the numerical simulation of Navier-Stokes equations, the choice of the mesh type plays a significant role. Comparative calculations on different mesh types illustrates that the best simulation precision, characterized by minimum Local Truncation Error (LTE), is obtained on Cartesian meshes. For the boundary representation the Immersed Boundary (IB) approach, which does not require a boundary-conforming mesh, is used. Use of Cartesian meshes together with Immersed Boundary approach makes it possible to efficiently: minimize approximation errors; build operators with good spectral properties, so that robustness of method is guaranteed; speed up the process of grid generation; and make grid generation robust and flexible. Many other CFD methods require a mesh that fits the boundaries of the computational domain and often complex internal geometries. The body-fitted grid generation used is time-consuming, often requiring manual intervention to modify and cleaning-up the CAD geometry as a pre-requisite.

To implement the IB approach efficiently in FloEFD, a number of issues needed to be resolved: approximation of the governing equations in cut-cells that contain the solid-fluid interface; capture of boundary layers effects irrespective of boundary layer thickness using a Two-Scale Wall Functions (2SWF) approach (see Mentor Graphics Corp., 2011); automatic mesh generation with automatic detection of initial mesh settings (octree-based mesh structure); and Solution Adaptive Refinement (SAR).

Test cases given in this paper represent a small selection of our validation examples that illustrate the IB approach precision and flexibility of FloEFD meshing technology in the wide range of industrial examples of geometry and physical formulations.

Every form of electric lighting produces an unwanted by-product: heat. In the case of incandescent and fluorescent lighting, generations of engineers have developed ways to minimize and/or divert heat from luminaires and fixtures. But LED lighting, appearing today in growing quantity and variations, poses new and different challenges. Heat buildup can reduce an LED’s light output and cause a color shift and at the same time, shorten the component’s useful life. It has been said that thermal management is by far the most critical aspect of LED system design. From an engineer’s perspective, this may mean learning to work with tools and procedures that go beyond the comfortable realms of mechanical and electronic design. Fortunately a host of thermal design solutions is ready to help simplify the engineer’s journey through thermal validation and measurement challenges.

This paper explains how Concurrent Computational Fluid Dynamics (CFD) technology has become a cornerstone for aerospace mechanical design today. Designers must perform flow analysis on a broad range of components and subsystems such as hydraulic valves and cockpit ventilation systems. Almost all aircraft elements that come into contact with liquids or gases or that conduct heat from a device will require fluid flow analysis. Thus, flow analysis will help engineers save cost, time and weight in their aerospace system design by revealing hidden design weaknesses and enabling the designer to optimize the design for greater performance.

Concurrent CFD is a new kind of CFD tool that enables mechanical engineers to simulate the flow of fluid and heat transfer for today's products using 3D CAD models. One of the most critical steps in this process is meshing and establishing an effective grid system for 3D simulation and analysis. This paper discusses why automated adaptive meshing is advantageous and how new designs can be meshed most effectively to dramatically reduce the time needed for accurate analysis and to increase design productivity.