If you have been using ANSYS Fluent for a while, you must have heard of the effectiveness of User Defined Functions or might have used one to enhance your simulation. This is where the real power of the software is. User defined functions (UDF) allow you to modify the behavior of ANSYS Fluent to satisfy your particular modeling needs. For example, these modifications may be used to impose desired initial and boundary, material models as well as various physical and chemical transformations such as heat transfer, chemical reactions or phase change. UDFs are flexible and powerful, and allow you to use ANSYS Fluent as a framework to implement new models.
The process of writing these functions is well laid out in the documentation; yet it still requires careful attention and proper coding protocols to produce the maximum benefit. To this end, we have gathered a team of senior engineers who will present webinars on how to effectively write UDF’s to address specific needs. Continue reading
Spray modeling has been a hot area of research especially in aerospace and automotive industries. The need to resolve the early development of sprays in the near nozzle area has grown steadily. However, this is a challenging area of modeling as resolving the liquid-gas interface is non-trivial due to complicated physical processes involved. Any modeling tool employed for this problem must be able to address the discontinuity in material properties at the interface as well as the effects of turbulence and surface tension forces at the interface.
There are some approaches that you can use currently in the context of CFD modeling. As a first approach, ANSYS Fluent’s DPM model offers something called “Atomizer” models that provide PSD based on the type of nozzle and some nozzle operational/geometrical parameters.
A second, more detailed approach is to use the VOF multiphase model to capture the liquid-gas interface at the droplet level. This requires a very fine mesh in the shear layers and hence is prohibitively expensive if entire length of the spray needs to be captured. Continue reading
Our existence depends on reactions. They are all around us. Driving to work, we convert the hydrocarbon fuel through a combustion reaction into water vapors and carbon dioxide. In the case where you have those fancy hybrids or electric cars, you still need that electrochemical reaction to take place to draw current and run the electric motor.
We breath air. The oxygen in air helps in burning the glucose in our body and provide us with energy. So, be it a very complicated engine or a biological system like humans, reactions are everywhere. Continue reading
This week, I attended the American Flame Research Committee’s Combustion Symposium in Houston where I presented a paper on radiation modeling.
Most of the papers presented were about industrial flares. If you live near a process plant, you must have seen these large stacks reaching into the clear blue sky. At the end of these stacks are large flames that can be seen from a distance. For most urban area residents, these flares create a concern about public health and safety especially if there is some black smoke as well in the fireball.