Fluid Thinking

Fluid Thinking is a shared blog that will discuss aspects of thermo-fluid simulation at the system level, with a specific focus on the application of Flowmaster in the aerospace, automotive, defense, energy, and plant & process industries. Ultimately the purpose is to share ideas, pose questions, provide insight, and facilitate discussions that lead to a greater understanding of the 1D computational fluid dynamics arena for all.

10 October, 2014

Hi I’m Chris and I’m a Fluid Systems Engineer.  I didn’t plan on becoming one on graduating from University and didn’t really know what one did but bluffed my way through an interview and got offered a job working for Flowmaster as a support engineer.  It can be difficult to explain to friends, family and customers exactly what I do and where a tool such as Flowmaster is used beyond ‘Virtual Plumbing’.  I thought my first post on the Fluid Thinking Blog might be a place to start.

When people hear the phrase CFD they immediate think of 3D CFD tools such as FloTherm and FloEFD that are used to model problems in a three dimensional space, this can be either external flow (over and around the object being modelled) or internal flow (confined within the model).  A 1D system tool such as Flowmaster is different, to build a model the user builds a system from a selection of components each modelling the internal flow within a component.  The components are connected together to form a network and the network is then run through a series of scenarios and the results analysed.  The systems modelled are more often than not those you don’t see or think about but don’t want to fail such as the fuel system on an aircraft, the lubrication system in the engine of your car or the cooling system of a power station.  It’s the unglamorous downstairs to 3D CFDs glamorous manor house, alot of work happens but it’s largely unseen.

When someone passes me a picture or diagram and asks ‘How can you model that in Flowmaster?’ the first question I’ll ask is what do you want to use the model for?  Is it for an initial sizing study to specify a pump or heat exchanger, is it looking at how a model reacts with time to external event or what happens if we run the system with a different fluid?  Once I know this I’ll start mentally breaking it down into smaller sections, pipes and valves can be pulled from a catalogue directly but some things may need to be built from a combination of components.  The example below shows how the muffler (silencer) in the exhaust of a car modelling the expansions, baffle plates and contractions into the chambers within it.

muffler

This breaking things down into elements from lumping everything into a single loss to breaking it down into smaller elements as was done in this example where more detail is required, this often happens as the project progresses.  An example here would be modelling an aircraft fuel system where you start with a single tank to represent a wing tank in an initial model then breaking it down into individual tanks to represent cells within the wing and looking at the flow between them through a flight cycle. Talking to colleagues who’ve moved from 3D CFD to system simulation this breaking it down into components is stage that takes longest to get a grasp of.

The second question I’ll ask is where I can get the data to characterise the components.  Flowmaster components are pre-loaded with data from Internal Flow Systems that provides a good starting point, however for the best results data for the actual components is needed.  This data might come from the manufacturer, test data or more recently CFD with automated tools built into Flowmaster for the import of data.

As a person with little patience and a short attention span one of the attractions of working with a 1D model is the speed at which you can access results. For a steady state simulation the time from pressing run to get a result is usually measured in seconds, for a transient it’s usually minutes rather than hours.  This speed of results is one advantage over 3D CFD meaning it’s possible to run through many potential configurations in a short period of time quickly to optimise a model.

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5 September, 2014

Do you have an upcoming project and don’t have a tool that can handle system level thermo-fluid analysis? Are you evaluating your current simulation options to make sure they meet the needs of your business for years to come? Are you curious about new ways of solving problems of the world today in particular with the use of CFD?

If you are like most engineers I speak with, the process for getting access to high quality software can be tedious. Even if you are able to get access to a demo version of a tool, the overhead of going through IT to get software installed on your machine or to have the licenses available on the server can easily reduce that precious evaluation time you set aside from a matter of weeks to a matter days. This is hardly enough time to get a good understanding how well a tool can meet your needs.

That’s why Mentor Graphics has launched the Flowmaster Cloud-Based Free Virtual Lab which you can access here.

flowmaster-vlab7

As part of the Virtual Lab you will have immediate access to all the files and licenses necessary to run Flowmaster from any current PC web browser. It also includes guides and example models to help you construct your first system simulation in Flowmaster while you are at work, home, or even while traveling. With Virtual Lab you now have the ability to evaluate the future benefit you can get from system simulation at your own pace.

Also, if you require access to a 3D CFD solver try out the Virtual Lab for FloEFD, the fastest CFD solution from MCAD model to manufactured product.

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14 February, 2014

Do you know someone who had issues with an automobile overheating or an issue with a sump pump?  What about someone who has flown on an aircraft or even used electricity?

If I had to take a not so wild guess, I would bet that most people out there with the ability to read a blog post would answer yes to at least one of these questions.  This is good because it means you have at least indirectly experienced the potential benefit of using system level thermo-fluid simulation.

Also referred to as 1D computational fluid dynamics (CFD), tools like Flowmaster help engineers in a wide range of industries to better understand how their systems will behave.  If we look at the example above of an automobile overheating, this is a perfect area for thermo-fluid simulation.  From the beginning engineers can start to size the system, selecting the optimal radiator, oil cooler, fan, and other heat exchangers to work with the engine under normal operating conditions.

Once a preferred initial design is selected, the system can be exposed to what-if scenarios beyond its normal operation.  How does the system behave if the fan relay stops working?  What happens if the thermostat gets stuck open?  Exploring critical scenarios such as these earlier in the design process with Flowmaster means companies can get more robust designs put together before building expensive physical prototypes often referred to as system driven design.    Over the design process, this potential means a better final design in a shorter design window with less upfront cost; certainly a win-win for all involved.

This is just one example of where Flowmaster (and system simulation as a whole) has made a difference in the lives of engineers across a wide range of industries.  As the blog continues we will be focusing on different areas where the use of thermo-fluid software in the design process improves the way systems behave and the effect that has on the world as a whole.  We will of course discuss other interesting aspects of engineering and CFD as a whole and I would like to invite you all to be a part of the discussion not only on simulation driven design but on system simulation in general.

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