Driven by the twin demands of evolving customer expectations and increasing emissions regulation, the global automotive industry is in a race to deliver a sustainable compliment (if not replacement) to the Internal Combustion Engine. For now, propulsion systems based partially, or entirely, around electricity seem like the most credible prospect for providing the greatest reduction in CO2 emissions, within a reasonable timescale.

However, compared to gasoline engines, the cost of electrified power trains remains high, mainly due to the high cost of the batteries required to store and deliver the electrical power needed to drive such vehicles. Both Automotive OEMs and battery manufacturers are investing heavily in battery technology, with the aim of extending battery life, achieving higher energy densities and faster charging times, while improving both safety and reliability. A lot of this investment focuses on the efficient thermal control of battery cells.

Temperature distribution analysis of a module of 84 cells: 42 cells connected in series, and each row is connected in parallel. Liquid cooled plate are lateraly postionned on those rows (Image courtesy of ASCS, Stuttgart and Behr)

When Dave Brailsford announced the formation of Team Sky in 2010, he did so with the explicit ambition of propelling a British rider to the top step of the Tour de France podium by 2015. To cycling experts, it seemed like a brave and almost foolhardy prediction. In the 97 editions of the Tour de France that preceded Brailsford's announcement, no British rider had finished in the top 3 of the world's most important cycle race, let alone threatened to win it. Therefore, it seemed unlikely that Brailsford - a newcomer to the world of professional cycling would be able to reverse that lack of fortune in such a short period of time.

PinelloThe experts were wrong and spectacularly so. This Sunday as the Tour wrapped up its 100 year anniversary (two years ahead of Brailsford schedule) Team Sky rider, Christopher Froome rode into Paris wearing the coveted yellow jersey on his shoulders with a comfortable 5 minute margin over the second place rider. In doing so, he claimed not the first, but the second consecutive victory for a British Team Sky rider at the Tour de France, following in the footsteps of last year's winner Sir Bradley Wiggins.

So how did Team Sky manage to beat their own prediction and deliver a double British victory two years ahead of their plan?

How Do You Consider Surface Tension Effects Between Particles When Using DEM?

In STAR-CCM+, we can model the effect of the presence of the liquid film on the surface of DEM particles in the approximation of liquid bridge model. 

The capillary force resulting from the surface tension and the pressure difference inside the liquid bridge has known dependence on the wetting angle, liquid surface tension, particle size, etc.

If one assumes particular shape of liquid bridge, the solution of Laplace-Young equation provides the solution for hydrostatic pressure within liquid bridge. This gives the analytical solution for the maximum force needed to separate two particles connected with liquid bridge (lots of literature is available on this, including using liquid bridge model with DEM). Now, you just need to equate the liquid bridge force with STAR-CCM+ expression for linear cohesion force and voilà! - obtain the value of STAR-CCM+ cohesion parameter. Using cohesion model this way should account for the surface tension effect on the bulk flow of wet grains.Liquid Bridge

After explaining why simulating a pool break is so difficult in my last blog post, I couldn't resist actually performing the simulation using Discrete Element Modelling in STAR-CCM+.

I've always been a terrible pool player. Until recently, I attributed this complete lack of talent to my abysmal hand-eye coordination skills. As it turns out, I may have been too hard on myself in that my inability is almost entirely due to the fact that I generally fail to properly take account of all the physical phenomena that influence the pool table when making a shot. More specifically, it's because I usually neglect to to take account the gravitational attraction of the big dude sitting at the opposite corner of the bar. In the past few blog posts we've talked about the importance of 'simulating the system', the process by which we try to account for all the factors that are likely to significantly influence the performance of a design in operation, and how failing to account for some of those physics can reduce the accuracy of your prediction. Exactly the same principles apply when lining up a pool shot!

Pool Break

On paper at least, calculating the elastic collision of two pool balls is a relatively trivial task. Let me explain…

Over the last couple of days, the “World of CFD” has been buzzing about our recent acquisition of Red Cedar Technology. The word “acquisition” can sound a little frightening as it’s often associated with mis-management, changes to the way customers interact with vendors and a myriad of other oh so fearful changes. Anyone old enough to remember that debacle in the 1980’s between Bendix and Martin Marietta (one of the most complicated takeovers in corporate US history) knows what I’m talking about.

Twelve months ago, Red Cedar Technology and CD-adapco announced a partnership to expand multidisciplinary process automation and design exploration.  We had a clear vision for how to enable engineers to quickly discover better designs rather than spend the majority of their time on tedious model building and validation.

This vision comprised solutions for the following typical obstacles to broad-based design exploration:

Last week we announced the release of STAR-CCM+ v8.04, the second of our three v8 series for 2013. I can see from the download logs of the Steve Portal that many of you downloaded the new version within the first few minutes. I hope you are enjoying all the new features and enhancements. While I could talk at length about these new bells and whistles, I'd prefer to explain the rationale behind STAR-CCM+ v8.04, and explore the philosophy of our development strategy.

One of the consequences in maintaining our aggressive release cycle is that it’s easy to become distracted by the list of individual features that arrive thick and fast every four months. One may miss the bigger picture of what we are trying to achieve.  You see, very few new features in each release are 'one-off enhancements.' Most of them could be better viewed as building blocks towards a larger development objective (although we do hope that many of these new features are instantly useful).

We've all been mesmerized for years by that thing of beauty rising out of the water majestically in that James Bond movie... If you're thinking Ursula Andress or Halle Berry or Daniel Craig, think again. I'm an Engineer and to me, the submarining Lotus Espirit from The Spy who Loved Me is my equivalence of a teenager's infatuation with water entry of matinee idols. In my fantasy world, my car would run on road, swim in water, fly in air and even brew me a nice, cold beer while I watch football. The Lotus Espirit ticked off two of those boxes quite handsomely.

When I was tasked with showing off new application areas with STAR-CCM+’s Overset Mesh feature, I scoured the internet for a model of the Lotus Espirit. In the end, I had to settle for a worthy substitute, the Assault Amphibious Vehicle (AAV7A1) used by the United States Marine Corps. The engineering design challenges for an amphibious vehicle are primarily the reason they are few and far between. In the case of vehicles like the AAV7A1, requirements of dual capability of speed in water and land in extreme conditions combined with a light armor to keep the weight down result in working within a tight design space. One of the major concerns when designing such a vehicle is the crossing from land to water or vice versa. Safety of the crew and the vehicle as a whole is of paramount importance when crossing into a different environment.

Water entry simulation

Numerous parameters play a role in the vehicle’s behavior when entering water or land: vehicle speed, direction relative to water and slope of the beach being the most important. Key factors in assessing the safety of the beach ingress are the maximum pitch and roll angles as the vehicle enters water, maximum accelerations on the vehicle and flooding of engine and passenger compartment. The body shape, weight distribution and size of the vehicle are already defined based on the mission requirements to achieve proper performance for land or sea. Safety tests are usually done on a prototype in a test basin using varying angles of ground slope and speed for entry into the water.

Simulation of water entry is currently being used in analysing the vehicle body shape; correcting for proper trim, body accelerations and flooding behavior before testing a prototype. Amphibious vehicles are well known for ballooning design times and project costs stemming from extensive testing for adequate safety. Simulation can reduce both time and cost, while giving insight on vehicle behavior.

Brigid Blaschak
Communications Specialist
Dr Mesh
Meshing Guru
Stephen Ferguson
Communications Manager
Tammy de Boer
Global Academic Program Manager
Sabine Goodwin
Senior Engineer, Technical Marketing
Joel Davison
Product Manager, STAR-CCM+
Matthew Godo
STAR-CCM+ Product Manager
Prashanth Shankara
Technical Marketing Engineer