Special Coverage


Explicit Filtering Leading to Grid-Spacing-Independent and Discretization-Order-Independent Large Eddy Simulation Solutions

Two-phase volumetrically dilute flow with evaporation is addressed. NASA’s Jet Propulsion Laboratory, Pasadena, California Numerical simulations for turbulent flows using the most promising methodology, Large Eddy Simulation (LES), are grid-spacing and discretization-order dependent. This means that the solution is not trustworthy and cannot be compared with experiments to determine the validity of the mathematical model.

Posted in: Briefs, Electronics & Computers, Simulation Software


Explicit Filtering Leading to Grid-Independent and Discretization-Order-Independent Large Eddy Simulation

The re-formulation involves explicit filtering of the conservation equations. NASA’s Jet Propulsion Laboratory, Pasadena, California To validate simulations, one must trust that they are independent of the numerical aspects. A very promising, relatively new methodology for simulating turbulent flows, called Large Eddy Simulation (LES), has some issues in this respect. The issues stem from the aspect that modeling and numerics are totally intertwined, resulting in the fact that the results are grid-dependent and discretization-order-dependent. These issues were described in the preceding article. These issues prevent LES validation with experiments since one can always make adjustments to agree with data, which is not validation.

Posted in: Briefs, Electronics & Computers, Simulation Software


Mars Science Laboratory Second-Chance Flight Software

NASA’s Jet Propulsion Laboratory, Pasadena, California Mars lander spacecraft, beginning with Mars Pathfinder (MPF), have been designed to tolerate flight computer resets during the entry, descent, and landing (EDL) phase despite having only a single flight computer. This capability was enabled by a predictable, non-dynamic EDL architecture. The Mars Science Laboratory (MSL) spacecraft has a highly dynamic EDL architecture as well as dual flight computers, adding more complexity to EDL flight software fault tolerance.

Posted in: Briefs, Aviation, Electronics & Computers


Multi-User Investigation Organizer

Ames Research Center, Moffett Field, California InvestigationOrganizer (IO) is a Web-based information system that integrates the generic functionality of a database, a document repository, a semantic hyper-media browser, and a rule-based inference system with specialized modeling and visualization functionality to support mishap investigations. The semantic hypermedia component includes a customizable ontology that specifies various types of items (people, places, events, causes, systems, and associated information products) relevant to mishap investigations. The ontology also describes important properties of each item type, and details the potential relationships among items.

Posted in: Briefs, Electronics & Computers


Unit Conversion Macro for TecPlot Solutions for CFD

Lyndon B. Johnson Space Center, Houston, Texas The invention is a TecPlot macro, which is a computer program in the TecPlot programming language that processes CFD (computational fluid dynamics) solutions in TecPlot format. The TecPlot data is in SI units (International System of Units) [same as CFD solutions]. This invention converts the SI units into U.S. customary units.

Posted in: Briefs, Electronics & Computers, Mathematical/Scientific Software


Products of Tomorrow: February 2015

The technologies NASA develops don’t just blast off into space. They also improve our lives here on Earth. Life-saving search-and-rescue tools, implantable medical devices, advances in commercial aircraft safety, increased accuracy in weather forecasting, and the miniature cameras in our cellphones are just some of the examples of NASA-developed technology used in products today.

Posted in: Articles, Products, Data Acquisition, Detectors, Sensors


NACA to NASA: 100 Years of Aeronautics Innovation

Streamlined aircraft bodies, quieter jet engines, techniques for preventing icing, drag-reducing winglets, lightweight composite structures, and so much more are an everyday part of flying thanks to NASA research that traces its origins back to the earliest days of aviation.

Posted in: Articles, Aviation