Tips & Tricks

Parallel processing

“To pull a bigger wagon, it is easier to add more horses than to grow a gigantic horse.” This paraphrased quotation nicely expresses the basic concept of parallel processing. The speed of sequential computers has been doubling every eighteen months, according to Moore’s law. However, at any given time, that speed is limited by the state of the art in integrated circuit design and manufacturing. To circumvent that limitation, it is possible to split a given computationally intensive task among multiple processors working simultaneously.

The manufacturing of sand cores

The manufacturing of iron, steel and non-ferrous castings is achieved using a variety of casting process designs, and most of these involve the use of sand cores which form the internal shape of the casting. A good quality casting requires a good quality core. Dimensional stability, uniform density, strength, hardness and permeability are some of the characteristics that need to be controlled. A good core must have suffi cient strength and hardness to be handled and to resist during the pouring of liquid metal. Suffi cient permeability is also necessary for the escape of gases generated during the casting process. The diff erent manufacturing processes and some of the issues related to core production will be discussed here.

FLEXlm protection file system

ESI group needs to license, manage and track a variety of licensing options, platform and product dependencies. FLEXlm is one of the only software that is up to this task. A simple, shrinkwrapped license management product would not be powerful and flexible enough to license all ESI products.

Why it is useful to describe problems in terms of non-dimensional parameters and which ones are the main important in solidification?

A dimensionless quantity is a quantity without any physical units. Such a number is typically defi ned as a product or ratio of quantities which do have units, in such a way that all units cancel. Dimensionless quantities are widely used in the fields of physics and engineering but also in every day life.

CFD-FASTRAN/CFD-ACE+ coupling for thermal environment simulations

In certain applications, different regions of the computational domain experiences flow conditions that are so different that it is very difficult for a single solver to produce accurate results at the extremes. In many situations, such problems can be separated and solved using loosely coupled solvers. Each solver is chosen to provide highly accurate solutions for the prevailing flow conditions.

Avoiding Chimera Errors in CFD-FASTRAN

This note discusses a common error encountered by users when trying chimera meshes in CFD-FASTRAN. Such errors are easy to avoid and hopefully this note will assist you.

Motion Model Dependencies in CFD-FASTRAN

Moving-body models available in CFD-FASTRAN are highly suited to simulate complex prescribed and six-degree-of-freedom (6DOF) motions of rigid bodies. In many engineering problems, this translates to multiple bodies moving relative to one another.

Low Mach Preconditioning and Dual Time Stepping in CFD-FASTRAN

Density-based schemes employing time-marching procedures available in CFD-FASTRAN provide excellent stability and convergence characteristics for high-speed compressible flows (typically M >0.5).

Axisymmetric 2D Convergent-Divergent Boattail Nozzle Simulation Using CFD-FASTRAN

The NASA D-1.22-L boattail nozzle configuration was obtained from the MADIC (Multidisciplinary and Design Industrial Consortium) program. The geometry definition and the flow conditions are documented in NASA TP 1766 [1]. This user tip presents a validation of numerical methods against experimental data.

Chemical-kinetic Model for Mars Atmosphere Re-entry Applications

The shock layer flow over a blunt body entering a planetary atmosphere at a hypersonic speed will dissociate and partially ionize. A reliable prediction of the flow-field for such application requires a chemical-kinetic model. For Mars atmosphere, the five species Park'94 is considered [1]. The dissociation of CO2 is producing C, CO, CO2, O and O2.