Vinh-Tan Nguyen and co-workers at the A*STAR Institute of High Performance Computing in Singapore have developed a more robust and efficient way to simulate shockwaves under various flow scenarios. Previous techniques for shockwave simulation are specific to particular flow problems, whereas this new method is applicable to shockwaves in any high-speed flow scenario, for example in aerodynamics or explosions.
Simulations of shockwaves in fluids as they initiate (left) and propagate (right), using a specially tuned computational mesh.
Copyright : 2013 A*STAR Institute of High Performance Computing
A shockwave is generated when a discontinuous change in fluid properties follows an abrupt increase in the pressure, temperature and density of the flow. “Strong and unsteady shockwaves can produce oscillations, which affect the stability of numerical solutions in the three-dimensional (3D) computational domain,” explains Nguyen. “The main aim of our technique is to resolve the front of a shockwave while preserving the overall accuracy of the simulation.”
In computational fluid dynamics, flows can be simulated with different levels of accuracy — a low-order approximation is based on a hypothesis, whereas a high-order approximation is one that is closest to reality, or the ‘finest-tuned’ approximation. Simulation accuracy is maintained by using as high-order approximation as possible, as well as by altering the resolution of the 3D computational mesh — a grid of interconnected data points that covers the spatial area of the flow.
“Simulating flows using high-order approximations triggers oscillations, which cause miscalculations at the front of shock waves where the flow is discontinuous,” explains Nguyen. “It therefore becomes counterproductive to have high-order approximations in place right across shock regions.”
To overcome this problem, Nguyen and his team placed a shockwave sensor within the flow to identify high-gradient shockwave fronts as they appeared. They then applied shock capturing schemes to resolve the fronts by reducing the approximation order in those specific regions.
Finally, the researchers increased the spatial resolution of the computational mesh in the localized shock areas to compensate for the lower-order approximations (see image). The 3D mesh is also programmed to rebuild itself following contact with a shockwave.
“With precise detection through the shockwave sensor we can apply the right capturing scheme to treat each shockwave, regardless of its strength,” explains Nguyen. “Our mesh adaptation procedure then simultaneously refines the mesh in shockwave regions and coarsens it in areas of least change, reducing computational costs significantly.”
In addition to its potential application in aerodynamics and blast analysis, the researchers believe that this scheme may be useful for simulating the interface between air and water, with huge potential for marine and offshore applications.
The A*STAR-affiliated researchers contributing to this research are from the Institute of High Performance Computing
Nguyen, V.-T., Nguyen, H. H., Price, M. A. & Tan, J. K. Shock capturing schemes with local mesh adaptation for high speed compressible flows on three dimensional unstructured grids. Computers & Fluids 70, 126–135 (2012).
Information integration and artificial intelligence for better diagnosis and therapy decisions
24.05.2017 | Fraunhofer MEVIS - Institut für Bildgestützte Medizin
World's thinnest hologram paves path to new 3-D world
18.05.2017 | RMIT University
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy