Written by Aisling Hughes on August 14, 2019
June 12th, 2019
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CFD is the acronym for ‘computational fluid dynamics’ and, as the name suggests, is the branch of fluid mechanics that makes use of computers to analyze the behavior of fluids and physical systems. CFD analysis became a popular solution as the difficulty grew in applying the laws of physics directly to real-life scenarios in order to make analytical predictions. This fact became especially prevalent for fluid flow and heat transfer engineering problems.
Fluid mechanics is the science that studies the physical behavior of fluids: liquids, gases, and plasmas. As such, it relates the forces acting on a fluid body and the consequent changes in internal fields such as velocities, pressure, density, and temperature. These relations are mathematically stated through differential equations, the Navier-Stokes equations being the corollary of the known laws for the behavior of viscous fluids:
On the other hand, heat transfer is the study of how thermal energy gets generated, stored, transported, and transformed. The main mechanisms it analyzes are:
Laws of physics for fluid flow and heat transfer are expressed in terms of differential equations, most of the time with many related variables. It happens to be that some of the equations for both fields are similar; for example, the diffusion of a scalar through a flow field and the diffusion of temperature.
The most general of these laws for the flow of fluids is the set of Navier-Stokes equations. Yet due to their complexity, solving these equations for exact solutions can only be achieved for the simplest of cases.
This is where numerical analysis and computers come in to play. By using numerical approximations, CFD turns the full differential equations into systems of linear equations, which are then solved to obtain field values such as velocities, pressures, and temperatures on a finite (but often large) number of points in the domain of the problem.
Although numerical methods for obtaining approximate solutions to differential equations have existed for many centuries, the ability of computers to store large amounts of numerical data and perform fast operations on them is what has turned technology into the most practical tool for physicists and engineers. At the same time, this means that one often finds that the application of CFD to practical problems is limited by the computational power available.
CFD analysis allows for the modeling of fluid because of its versatility in numerically solving equations of state and physical behavior, expressed in differential or explicit form. Also, as heat transfer problems are of paramount practical relevance, any competent simulation tool includes modules to calculate temperature distributions alongside pressure and velocities. Also, some applications can also include analysis of solids for elastic deformation or chemical reactions, among other non-fluid applications.
Learn how to use CFD analysis to understand the behavior of the airflow around an F1 car.
There are many CFD software offerings in the market, some of them of general purpose with many capabilities and some tailored for specific applications. Companies even develop their own in-house codes for specific engineering tasks. Here is a list of the most used, general purpose suites in the industry:
A very good alternative to traditional, desktop workstation-based suites is the cloud-based simulation platform SimScale. It is built upon established solvers including OpenFOAM, providing an easy workflow, a modern user interface ran from the web browser with computations run from remote servers and relieving your local machines from intensive and lengthy tasks.
Here are some of the most representative industrial sectors leveraging the power of CFD analysis, and a short description of why they do it:
The automotive industry makes use of CFD for many applications, with the most important being vehicle aerodynamics. CFD analysis is used to predict drag, downforce, and stability against cornering/crosswind flow. Other automotive applications include engine combustion and thermal performance, ventilation, exhaust fumes and more. Here is a link to an example project simulating the aerodynamics of an F1 car.
In the aviation industry, the main application of CFD is also aerodynamics, with the aim of optimizing the lift/drag ratio and to study instabilities. Here is an example project on airplane aerodynamics, that touches on how simulation can give valuable insights into airflow and aircraft performance. Other important fields for simulation within the aviation industry includes ventilation and air filtration.
In the manufacturing industry, CFD is used to study the performance of the cooling system in consumer products, especially those making use of electronics. Here is an example project—enclosure design for a Raspberry Pi.
As product development cycles are getting shorter in time, and as more and more products rely on precise performance to achieve success, numerical simulation is always gaining more relevance. Its ability to make precise performance predictions with fast, reliable and easy workflows unleashes the possibility of carrying optimization right from the engineer’s workstation, even before the first prototypes are built.
CFD simulation is not the exception to this trend and with offerings such as SimScale, which brings lots of computational power and optimal workflow at affordable prices, without the hassle of complex software and hardware installations, these advantages are reachable to a larger number of companies, even those on tight budgets.
If you wish to learn more about CFD and start leveraging its advantages for your projects, I recommend you to:
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