Computational Fluid Dynamics & Fire Dynamics Modeling


Computational Fluid Dynamics (CFD) is a tool used frequently in engineering. It can be applied to a wide range of problems and is particularly well-suited to analysis in which direct measurement is not feasible due to prohibitive cost, time constraints, or other practical limitations. At Exponent, CFD is also frequently used to supplement our analytical, experimental, and field-based capabilities when more detail is needed.

Exponent holds licenses for two major, commercially-available CFD packages: STAR-CCM+ and FLUENT. Our staff uses CFD in a wide variety of applications, including: modeling the multiphase flow of hydrocarbons through pipelines, drug elution from cardiovascular stents, flow through turbomachinery and aircraft engines, diffusion of carbon monoxide (CO), thermal management of electronic devices, venting of Lithium-ion batteries, and the spread of cryogenic liquids in trenches and sumps (see also our section on Computational Fluid Dynamics Modeling in Atmospheric Sciences).

Exponent also has experience using its CFD capabilities to perform design evaluations of consumer appliances and medical devices, as well as cause and origin determinations relating to fires and explosions.

Our fire modeling capabilities are frequently used to support fire cause and origin investigations. In this capacity, Exponent uses the most widely used tools in fire modeling—the Fire Dynamics Simulator (FDS) and the Consolidated Model of Fire and Smoke Transport (CFAST)—which are developed and distributed by the National Institute of Standards and Technology.

While FDS was originally developed for fire-driven flows, it is also applicable to non-fire-related scenarios, with the limitation of low-speed, thermally- or buoyancy-driven flows. Our engineers use FDS to model scenarios such as: fan-induced air flows, purging of large tanks, and the atmospheric dispersion of smoke and particulates over urban areas.

In addition to CFD and FDS, Exponent often constructs its own in-house codes to address specific needs. In particular, we have developed models for hydrocarbon spills in water and on the ground, and for the evolution of the hydrocarbon vapor concentration in a tank as a result of weather fluctuations and plant operating history.

Using these various computational analysis techniques, Exponent is able to investigate a wide variety of problems that would be impractical to assess experimentally. When experiments are too expensive or time consuming, CFD is a relatively cheap and quick alternative, allowing the problem to be analyzed over a wide range of parameters simultaneously.

Figure 1. Flow through a valve.

Figure 2. Lithium-ion battery venting. The color is proportional to the concentration of vented gasses.

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