Turbulence Part 4 - Reviewing how well you have resolved the Boundary Layer
In recent posts we have comprehensively discussed inflation meshing requirements for resolving or modeling wall-bounded flow effects due to the turbulent boundary layer. We have identified the y-plus value as the critical parameter for inflation meshing requirements, since it allows us to determine whether our first cell resides within the laminar sub-layer, or the logarithmic region. We can then select the most suitable turbulence model based on this value. Whilst this theoretical knowledge is important regarding composite regions of the turbulent boundary layer and how it relates to y-plus values, it is also useful to conduct a final check during post-processing [more]
Turbulence Part 3 - Selection of wall functions and Y+ to best capture the Turbulent Boundary Layer
In recent posts in our series of Turbulence Modelling posts, we have covered boundary layer theory and touched on some useful meshing and post-processing guidelines to check you are appropriately resolving the boundary layer profile. Today we will consider three critical questions that are often asked by CFD engineers when developing or refining a CFD simulation:
- Am I using the correct turbulence model for the type of results I am looking for?
- Do I have an appropriate Y+ value and a sufficient number of inflation layers?
- Am I using the right wall function for my problem?
This topic is so important because [more]
How does the Reynolds Number affect my CFD model?
The Reynolds number (Re) is the single most important non-dimensional number in fluid dynamics and is recommended to be calculated before you begin any new CFD modelling project. The Reynolds Number is defined as the dimensionless ratio of the inertial forces to viscous forces and quantifies their relevance for the prescribed flow condition:
Where U∞ and c are the characteristic velocity and length scale of the problem, ρ is the fluid density and μ is the dynamic viscosity. The use of the Reynolds number frequently arises when performing a dimensional analysis and is known as Reynolds principle of similarity. For example, [more]
Sir James Dyson was in Australia recently for the launch of Dyson's Airblade Tap hand dryer. During his visit, he gave a particularly enlightening interview with the ABC One-Plus-One program (which can be viewed at this link).
Dyson is a world-leader in the field of industrial design and is most famous for his invention of the cyclonic vaccuum cleaner (which now seems to have been copied and/or reverse engineered by all of his major competitors!). I'd suggest that the battles that Dyson has had on the Intellectual Property front are undoubtedly a factor that requires Dyson to keep ahead of the competition through constant innovation.
During the interview, Dyson [more]
Formula SAE teams aim for the podium with CFD
Budding F1 car designers & engineers here in Australia may be getting excited in the build-up to the first race of the F1 season with the Australian F1 Grand Prix being held in Melbourne next week (March 14-17), but many of them might also have another important car race in the back of their minds: the 2013 Formula SAE (FSAE) competition, which is the world’s largest student engineering design competition. Starting in 1979 but really gaining in popularity here during the past 15 years, Formula SAE invites highly-motivated engineering students from leading universities around the world to design, manufacture, test and race their [more]
Join LEAP at the 2013 Australian International Airshow
We know that many of our CFD customers are also very passionate about aerodynamics and aircraft design, so it stands to reason that the 2013 Australian International Airshow will be a magnet for both aircraft enthusiasts and CFD practitioners alike. The Australian International Airshow starts today (Feb 26th 2013) and LEAP Australia staff will be attending as part of the Victorian Government Stand, which is located in Hall 2, Stand 2F17.
If you are also attending the Airshow during the trade sessions this week (Tuesday to Friday), please drop us a line and we'd relish the opportunity to arrange a meeting and discuss your current CFD [more]
A commonly asked question is: What is Superficial Velocity and when do I use it?
If a fluid flows through a region that is occupied by either fixed structures (a porous region, pipe rack, catalyst bed, etc...), or shares the channel with other fluids (e.g. gas-liquid flow), there are two ways to describe the fluid velocity.
The first is to use the "True Velocity" which is the actual velocity of the fluid particles. This velocity will vary with location in the porous matrix. This is the velocity you would measure experimentally if you focused on a small region of fluid.
The second is the "Superficial [more]
(Part 2) 10 Useful Tips on selecting the most appropriate multiphase flow CFD models
As we discussed in our previous post, the first step when tackling a multiphase CFD problem is to identify the key characteristics of your physical system. Once you've done this (using our checklist if you are still new to multiphase CFD), you can begin to make informed decisions on what multiphase modelling approaches to use.
We've compiled the following guidelines based on the decades of experience that LEAP has developed while helping customers in Australia and New Zealand to solve multiphase CFD problems, particularly companies and researchers in the minerals, process and energy industries:
[1] If your problem involves a distinct free [more]
In advance of his visit to Australia in December, LEAP Australia is pleased to announce a webinar to be conducted by Dr. Markus Braun on Wednesday November 14th at 4pm AEDT (Syd/Mel daylight savings time). This webinar will provide an overview of multiphase flow modelling techniques and discuss recent advancements that impact the use of CFD in the minerals processing, energy and related industries.
Who should attend? This webinar is suitable for all engineers, researchers and managers involved in projects that include CFD modelling of multiphase flows.
About the presenter: Dr. Markus Braun studied mechanical engineering at RWTH Aachen, receiving his Diploma in [more]
10 questions to ask yourself when tackling your first (or a new) Multiphase CFD project
By virtue of the many physical processes we are often attempting to simulate in a virtual environment, CFD can be a complex beast. To accurately account for all real-world behaviour, the CFD engineer must consider the applicability of a large number of physical effects, including complex turbulence, compressibility, various modes of heat transfer and, last but certainly not least, the interaction of multiple phases comprising liquid, gaseous and solid components.
Even if you have mastered all of your geometry and meshing requirements, and undertaken many years of single-phase CFD simulations, it can still be a daunting task when you are asked [more]