What Is Computational Fluid Dynamics?

What is computational fluid dynamics (CFD)?

Computational fluid dynamics (CFD) is a computer-aided design (CAD) technique that utilizes simulation and analysis to calculate the behavior of liquids or gases in and around the vicinity of a product. CFD is a multi-physics solution due to its incorporation of various physical phenomena, including fluid dynamics, thermodynamics, and the conservation of momentum.

Similar to finite element analysis (FEA), CFD subdivides the fluid volume into smaller elements, which are then organized into a matrix. CFD has diverse uses such as weather forecasting, aerodynamics, and visual effects.

Why is computational fluid dynamics (CFD) important?

Computational fluid dynamics (CFD) holds paramount significance for several compelling reasons. It enables CAD users to visualize and analyze imperceptible elements within their designs, encompassing factors like air, the interior of bubbles, heat, nitrogen, oxygen, pressure, forces, and water.

By characterizing these intangible elements as "digital fluids" and incorporating their modeling into CAD systems, companies can realize substantial cost savings in hardware prototyping expenses.

To facilitate the modeling of digital fluids, whether within the internal volume, external volume, or a combination of both, the integration of an extraction tool within the CAD system is crucial. PTC offers two indispensable solutions for this purpose, namely Creo Flow Analysis and Creo Simulation Live.

Creo Simulation Live Advanced: fluid flow simulation

Fluid Flow Simulation allows you to factor in how your design interacts with fluid and iterate faster with real-time computational fluid dynamics feedback within your CAD instance.

With this feedback fully integrated into your modeling environment there is no more back and forth. When you change the design, you get guidance on the decisions you make in real-time. This allows you to quickly assess if you’re headed in the right direction, or if you should move on to the next iteration so that you can bring great products to market faster.

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Capabilities of computational fluid dynamics software

Get real-time computational fluid dynamics from Creo Simulation Live Advanced with Fluid Flow Simulation.

Fluid domain creation

Fluid domain creation in Creo Simulation Live Advanced involves defining the space for fluid flow analysis, setting boundaries, and specifying fluid properties, crucial for simulating and optimizing product performance.

External flow

In Creo Simulation Live Advanced, external flow analysis focuses on simulating fluid dynamics around a product. It's vital for understanding aerodynamics, optimizing designs, and enhancing product performance.

Internal flow

Internal flow analysis in Creo Simulation Live Advanced models fluid behavior within a product or system. This process aids in optimizing designs, ensuring efficient fluid transport, and enhancing overall performance.

Results display and interactive probes

Results display and interactive probes in Creo Simulation Live Advanced provide real-time visual feedback and data extraction, enabling engineers to quickly assess and improve designs for better product performance.

Fluid flow and temperature simulations

Fluid flow and temperature simulations in Creo Simulation Live Advanced enable engineers to analyze and optimize products by predicting how fluids and temperatures interact within various design scenarios.

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Streamlines, cut planes, particles, and direction fields in Creo Simulation Live Advanced offer valuable visualization tools to understand and analyze fluid flow, aiding in optimizing designs for enhanced product performance.

General process for CFD

Computational Fluid Dynamics can be executed by performing the following steps:

Start with a model

Before entering the CFD simulation environment, create the 3D CAD part or assembly to be analyzed. The geometry can be native to the CAD software or imported.

Define the fluid domain

The liquid or gas in the simulation can be either internal, like water flowing through a piping system, or external, like air flowing over the external surfaces of a vehicle. Define the volume region and apply material properties to the fluid, including density, viscosity, coefficient of thermal expansion, specific heat capacity, and thermal conductivity.

Establish boundary conditions

These represent the movement of fluids at the inlet and outlet of the analysis model and can be defined by flow velocity, inlet and outlet pressure, and mass flow. For internal flow, additional boundary conditions include swirl inlet (velocity with both normal and radial components), rotating wall simulating moving components, and gravity.

Prescribed temperatures can also be used as a boundary condition and thermal loads can be defined as heat flow, heat flux, convection, and convection radiation.

Perform the analysis

The CFD study can be run as either transient, to see the effects on flow and temperature as a function of time, or steady state to see the results at equilibrium.

Evaluate the results

As mentioned above, a variety of quantities can be displayed graphically in the model to provide an understanding of the system behavior.

Optimize the system

In real time, the CFD analysis updates with changes to your model, providing instant feedback for improving your model within its operating environment.

Applications of computational fluid dynamics

Incompressible and compressible flow

Applications of computational fluid dynamics encompass incompressible and compressible flow analyses. They assist in understanding and optimizing fluid behavior in various scenarios from aircraft aerodynamics to HVAC system design.

Laminar and turbulent flow

Computational fluid dynamics applications investigate both laminar and turbulent flow, essential for designing efficient transport systems, energy generation, and aeronautics, enhancing product performance and safety

Mass and thermal flow

Mass and thermal flow analyses help optimize systems related to heat transfer, chemical processes, and environmental engineering, facilitating efficient product design and resource utilization.

Advanced CFD: Creo Flow Analysis

Creo Flow Analysis (CFA) is a computational fluid dynamics (CFD) tool used to easily simulate fluid flow. This helps predict the performance of a system or product involving internal or external fluid flow and heat transfer. The analysis is enhanced by a validation and design optimization process without the need for extensive experience in CFD. The outputs from the simulation are used to study the performance of the system in detail and assist with modifying the design.

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Capabilities of Creo Flow Analysis

There are three packages of Creo Flow Analysis. The following are available in Creo Flow Analysis Basic, Creo Flow Analysis Advanced, and Creo Flow Analysis Premium:

Calculate internal and external flows
Animate flow results
Simulate flow
Heat transfer
Turbulence
Parallel processing simulation

Capabilities only in Creo Flow Analysis Advanced and Creo Flow Analysis Premium:

Particle: Simulate individual particles in the context of the flow
Radiation: Heat transfer due to emission of electromagnetic waves
Species: Simulating the mixing of liquids with similar densities
Moving/Sliding Meshing: Simulate the movement of individual components in a flow analysis

Capabilities only available in Creo Flow Analysis Premium:

Cavitation: Simulates vapor, free gas and liquid (bubbles) compressibility
Multiphase: Used when simulating gas and liquid together
Multicomponent: Another mixing capability used for multiple gases and density
Dynamics: Simulates interaction of fluids and solids

*For real-time directional guidance that includes computational fluid dynamics, please see Creo Simulation Live (CSL).

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Simulation case studies

Explore these case studies detailing how companies use PTC simulation solutions.

CUPRA optimizes design and manufacturing

Read our case study on how CUPRA optimizes vehicle component design and manufacturing with PTC Creo.

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Hill Helicopters designs personal helicopters

Visually stunning design meets top-class performance at Hill Helicopters, a start-up offering the ultimate in lifestyle accessory products.

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Recent advances in CFD technology

Traditionally, CFD was the realm of highly trained specialists. Yet, recent advancements empower designers and engineers to independently conduct CFD simulations. Moreover, what once took hours now takes only minutes or seconds, providing real-time design support.

Frequently asked questions

What is the difference between CAD and CFD?

Computer-aided design (CAD) and computational fluid dynamics (CFD) are distinct, yet interrelated tools used in engineering and design processes. CAD focuses on creating detailed 2D or 3D digital representations of physical objects, allowing engineers to visualize, design, and prototype products, structures, or systems. CAD is primarily concerned with geometry, dimensions, and spatial relationships.

CFD, on the other hand, deals with simulating and analyzing the behavior of fluids, such as gases or liquids, within or around these CAD-designed objects. CFD helps predict fluid flow, temperature distribution, pressure, and other parameters. While CAD creates the design, CFD evaluates its performance, optimizing aspects like aerodynamics, heat transfer, and fluid transport. In summary, CAD aids in design creation, while CFD focuses on evaluating how designed systems interact with fluids.

What are computational fluid dynamics used for?

Computational fluid dynamics (CFD) is a versatile tool used in various industries and applications. It is primarily used for analyzing and simulating fluid behavior, including gases and liquids. Key applications of CFD include aerodynamics in aerospace and automotive design, optimizing HVAC systems for energy efficiency, and enhancing the performance of turbomachinery like pumps and turbines.

CFD aids the pharmaceutical and biomedical fields in drug delivery analysis and blood flow simulation. CFD is instrumental in environmental studies, assessing pollutant dispersion and natural water flow. Weather forecasting relies on CFD to model atmospheric conditions. Additionally, CFD plays a vital role in industrial processes, such as optimizing combustion in power generation and assessing fluid dynamics in chemical engineering.

What are the governing equations of CFD?

Conservation of Mass: Continuity Equation

Conservation of Momentum: Newton’s Second Law

Conservation of Energy: First Law of Thermodynamics or Energy Equation

Can CFD help you?

CFD can be immensely beneficial in a wide range of industries and applications. Whether you're an engineer, scientist, or designer, CFD provides valuable insights into fluid behavior, offering solutions to complex problems. It helps in optimizing designs for improved performance, reducing the need for costly physical prototypes, and accelerating product development. CFD aids in understanding airflow, heat transfer, and pressure distribution, which is crucial in fields like aerospace, automotive, HVAC, and turbomachinery. It also plays a vital role in medical and environmental research, offering insights into drug delivery, blood flow, and pollutant dispersion. In essence, CFD is a powerful tool for problem-solving and innovation across various domains.

History of computational fluid dynamics

Computational fluid dynamics (CFD) is grounded in the Navier-Stokes equations, the foundation for modeling single-phase fluid flows. Simplifications lead to the Euler equations and the full potential equations by eliminating terms related to viscosity and vorticity. Linearized potential equations emerged for subsonic and supersonic flows. Early 2D methods, such as flow transformations around cylinders and airfoils, were developed in the 1930s. Lewis Fry Richardson's finite difference-based calculations and his book, "Weather Prediction by Numerical Process," laid the groundwork for CFD. CFD computations from the 1940s using ENIAC mirrored Richardson's techniques, shaping the field's evolution.

Computational Fluid Dynamics