What Is Simulation Approach and How Is It Beneficial in CFD Applications?

What is simulation approach and how is it beneficial in CFD applications.

This is the second part of a three-part series on the GT-Power modelling software. The first part on the introduction to GT-Power in CFD simulations can be read here. Simulation is a mathematical model where software is put to work to receive the desired outcome by solving mathematical equations. But the most crucial thing here is to capture the real physics behind the phenomenon. 

For example, if we consider the physics involved with the engine components, there are several phenomena taking place simultaneously. These include heat transfer in the exhaust manifold and water jacket, chemical kinematics in cylinder-combustion, fluid mechanics in piping systems, etc.

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So the point here is that something more than just a CAD software is required, something that can go hand-in-hand with the engineering expertise. That is why analysis software is rated much higher as it offers a systematic way of simulation approach, which can't be the case with CAD software.

Solving Navier-Stokes Equations Using GT-Power

The Navier-Stokes equations are a cluster of differential equations that were derived in the early 1800s. They represent the combination of all the forces that act on a fluid. They are considered to be the cornerstone of fluid mechanics. 

The GT-Power software is equipped with algorithms to solve problems based on Navier-Stokes equations. The role of an application engineer is to ensure that whether the selected components will give the desired performance or not while using the software. 

Significance of Navier-Stokes Equations:

• These equations are the mass, momentum, and energy conservation expressions for Newtonian fluids, i.e., the fluids which follow a linear relationship between viscous stress and strain.
• These equations are handy while solving incompressible or compressible, low or high speed, viscous or inviscid flows.
• Analytical solutions exist for simple problems, while complicated problems can be solved numerically.

Some of the complexities involved with Navier-Stokes equations are that there is no exact solution to these equations. That's the most prominent reason why these numerical techniques come into the picture.

Features and Capabilities of GT-Power

Some of the most useful features and capabilities of the software are:

• Efficient in finding Navier-Stokes flow solution, which simultaneously solves conservation of mass, momentum, energy, and species, and is uniquely stable.
• Solving problems related to integrated multi-physics fluid flow, thermal, heat transfer, chemistry, and much more.
• Full range of system analysis, detailed component design, HiL, and calibration.
• Built-in DOE and optimization package, offers links with the leading third-party optimization tools.
• Includes a tool-neutral XLink platform for co-simulation with other widely-used CAE tools such as Simulink, TAItherm, FEA, CFD, and others.
• A system simulation tool at its core, strengthened by the capability to perform full 3-D analysis (CAD, FEA, and CFD).

Applications of GT-Power 1-D Simulation Tool

The GT-suite provides a comprehensive set of validated 0D/1D/3D multi-physics component libraries, which can simulate the physics of fluid flow, thermal, mechanical, multi-body, structural, electrical, magnetic, chemistry, and controls.

Applications in the Engine and Machinery Domain

GT-Power finds its applications in the production and analysis of the following machines:

• On-highway vehicles like cars, trucks, buses, motorcycles, utility and commercial vehicles and their subsystems.
• Stationary machinery such as pumps, compressors, oil and gas piping systems, chemical processing plants, etc.
• Off-highway vehicles such as tractors, bulldozers, loaders, combines, mobile cranes, etc.
• Power systems such as generators, diesel engines, turbine engines, thermal management systems, mechanical drives, exhaust heat recovery systems, etc.

Why Is GT-Power a One-Dimensional Tool?

Choosing a 1-D software tool over the 3-D counterpart makes it easier to solve the mathematical equations and perform analysis. 

Since there are fewer variables involved in 1-D analysis, and there is no need to solve equations involving three dimensions, this technique helps reduce the overall simulation and analysis time tremendously. At the same time, it allows for fewer computational requirements. 

GT-Power, being a 1-D system simulation tool, makes it more permissive to analyze the entire engine path in one go. In short, GT-Power offers a simplified approach to solving Navier-Stokes equations.

Modelling Internal Combustion Engine Using GT-Power

A typical engine system modelling can be done effectively using GT-Power. A mathematical model can be prepared for the system easily and validated with the available test data for obtaining different sets of combinations that can influence engine performance. 

In this way, all the studies and analyses can be carried out mathematically using simulation without being performed physically.

Let's consider the combustion system of an engine. It is a crucial component of the engine since the overall engine performance depends on it. 

Combustion Processes

If there is complete combustion of fuel, then the exhaust will be clean; otherwise, it can lead to knocking in the engine, thereby deteriorating the mechanical efficiency of the system. So it's quite critical to capture the physics behind the combustion process so that an accurate mathematical model can be formulated for analysis. 

Air-Fuel Ratio

The most significant factor behind engine performance and emission characteristics is the availability of air. As such, maintaining the required air-fuel ratio is vital. 

GT-Power gives us the liberty to try and test distinct mechanisms like changing the valve timing, swirl duration, altering the wall opening and closing process, etc. so that we can analyze how much air should get into the engine cylinder. 

For this reason, there's no need to set up the real prototype. After analysis, one can optimize the wall timings and prepare the engine camshaft accordingly. 

Closing Thoughts

GT-Power is a one-dimensional system simulation software tool that is used extensively all over the world. Almost 85-90% of the automotive industry relies on the services of the software tool.

Multiple types of parameters like turbocharger selections, volume profiles, intake, exhaust valve timing, etc. can be studied at the same time with the help of GT-Power. Hence, the GT-Power simulation software tool can be put to use for any type of system ranging from a 250cc two-wheeler to a 13,000cc heavy-load truck.

If you're interested in doing a CFD course that combines theoretical as well as practical knowledge, visit Skill-Lync today.