Computational Fluid Dynamics Simulation

Computational Fluid Dynamics, or “CFD”, is a research field in the study of liquid and gas flows, in which massive processing units are used to solve the algebraic systems that represent the partial differential equations (PDEs) governing continuum media. Through CFD it is possible to obtain a detailed picture of a flow, whether its temperature distribution, velocity field, pressure, or even its effect on solid surfaces, such as lift or drag.

In the early days of CFD (1906), the “processing units” were schoolchildren carrying out basic arithmetic operations at scale; much has changed since then, but the ultimate goal of the technique has always been solving engineering problems. Back then, the problem was the design of a dam: a more accurate method than the simplified analytical approximations of the time was needed, after several dam collapses had already been observed in countries such as Egypt and the United Kingdom. This is why Lewis Fry Richardson turned to Euler’s proposal of applying finite differences to the solution of partial differential equations.

Today, both the method and the processor have changed, with finite volumes and multiprocessor computing units leading the way in solving systems of PDEs. CFD has become a cost-effective option within reach of small and medium-sized industry, through software that runs on personal computers, both desktop and laptop. The technological boom of the last 10 years in graphics cards has enabled the development of new algorithms, both for visualization and computation, fostering creativity and providing a competitive advantage in industry. A quick look at usage and investment statistics in CFD code development is enough to gauge its success and the competitive edge it offers.

You may be asking yourself right now,

When is it necessary to use computational fluid dynamics simulation?

Frankly, this is not a trivial question to answer. In the 1970s, Boeing and Airbus were competing to win the transatlantic flight market; the core engineering problem was the sudden increase in drag experienced by aircraft. A design that achieved low drag at near-sonic speeds would gain a competitive advantage through faster flights and reduced fuel consumption. This phenomenon, like any transonic flow problem, could not be solved analytically, and the usual alternative was experimentation. However, wind tunnels were unable to replicate the real flight conditions experienced by aircraft wings. This is how CFD provided a solution once traditional resources had fallen short. With this tool, design time was reduced from 3 years to 1 year, although the results were still far from exact.

Depending on the problem the technique is applied to, its application and accuracy must be adjusted accordingly, so that the expected results are obtained.