NASA Tech Needs

Advanced Computational Fluid Dynamics - Mesh Generation

NASA’s work in advanced aeronautics and space vehicle development relies on advanced Computational Fluid Dynamics (CFD) codes such as FUN3D that rely on numerical solution of equations of motion over a discrete mesh of points in three dimensions. A judicious placement of points is required to optimize computing efficiency without greatly reducing the sensitivity and accuracy of the calculations. Rapid generation of such a mesh and its subsequent adaptation to better resolve the problem physics are critical to the application of CFD to complex real-world problems of interest. What are the Challenges? Improved mesh generators are needed to support programs in aerothermodynamics and fluid dynamics in general. More specifically, an anisotropic 3D mesh generator (or re-mesher) is needed that can be driven by a spatially varying metric tensor field, and which specifies mesh spacing along three orthogonal directions. The mesh generator must accommodate cell aspect ratio requests of at least 10,000:1 even in the presence of a curved metric tensor field to enable high Reynolds number finite-volume CFD applications. Furthermore, in regions of high anisotropy (not necessarily bounded by a vehicle surface), mesh cells should be dominantly layers of semi-structured hexahedra or triangular prisms to allow non-dissipative capture of bow shocks, boundary layers, free shear layers, wakes, contact surfaces, and so forth. What is NASA Doing? NASA currently conducts aerothermodynamic and fluid dynamics analyses of vehicles (heating rates, pressures, etc.) through the use of state-ofthe- art CFD codes. The mesh generation methods in use primarily rely on advancing front/layer, and/or Delaunay algorithms to provide the mesh of points needed to describe the vehicle and the surrounding domain of interest for the analysis. While current methods have been successfully applied to complex problems, clearly additional research and development is needed in the area of mesh generation to reduce human involvement and increase robustness. We would like to provide uncertainty estimates (error bars) for the computational results delivered much like experimentalists do for their results. A critical component enabling this capability is mesh adaptation, whereby an existing mesh is adapted to improve the solution based on the problem physics and/or a solution error estimate. The criteria that drive the mesh adaptation are specified via a Riemannian metric tensor field. Within the field, a 3x3 (2x2 in 2 dimensions) symmetric positive definite tensor defines the desired local spacing constraints for the mesh whereby its eigenvalues represent the desired spacing along the direction of the corresponding eigenvectors. Current mesh adaptation technology in use does not easily allow us to do this in the presence of high element anisotropy in three dimensions while maintaining element quality. If the desired mesh generator can be developed, we will gain control over spatial discretization errors for CFD codes. This will allow us to focus on physical modeling errors and automate the process of obtaining a solution for a given application with bounded discretization errors. NASA’s immediate needs include CFD modeling of the exploration vehicles now under development to replace the shuttle for transport to the International Space Station and eventually for transport to the Moon and beyond, as well as advanced supersonic and hypersonic air vehicle development, both for NASA (Commercial) and military applications. The astrophysics, climate analysis, and hemodynamics (blood flow) fields may also have a use for such a capability, i.e., other types of fluid dynamics applications. More Information For more information, contact Dr. Bill Kleb at 757-812-1805 or nasa@techbriefs.com.

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Crush/Cut-Resistant Safety Glove

A company seeks existing materials that can be utilized in applications for a safety glove. This material must be cutresistant, flexible, and withstand oily, wet, muddy conditions. The material covering the top of the hand and fingers must be extremely flexible and designed to protect the hand and digits from being crushed by dispersing the area of impact from the initial blow. The mold for the top area of the hand must have emphasis on complete coverage without hindering normal movement. Respond to this TechNeed at: www.techbriefs.com/tn/200903d.html Email: nasatech@yet2.com Phone: 781-972-0600

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Topical Products to Suppress Pain During Epilation

A company is seeking topically applied products and/or chemical technologies to eliminate or suppress pain sensation associated with epilation of undesired hair from skin. Pain elimination or suppression should be quick (<5 minutes) upon application on skin, and the effect should be temporary (lasting about 30 minutes), similar to topical anesthetics. Products can be in the form of liquid, gel, cream, or lotion to easily apply or spray on skin; should not have any undesired side effects on skin (irritation, itching, redness); and derived from natural sources and with herbal properties. Respond to this TechNeed at: www.techbriefs.com/tn/200903c.html Email: nasatech@yet2.com Phone: 781-972-0600

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Highly Power-Aware Digital Extravehicular Activity (EVA) Radio

As NASA embarks upon deep-space human exploration, the next-generation extravehicular activity (EVA) radio will be a pivotal technology and an integral part of lunar surface systems success. It facilitates surface operations, enables crew mobility, and supports point to multi-point communications across rovers, landers, habitat, and other astronauts. Driven by Com - m unications, Command, Control, and Information (C3I) interoperability, stringent power budgets, and miniaturization, this mobile radio platform has become increasingly complex. To achieve the overarching communication goals of small form factor, ultrapower, and reconfigurability, NASA needs to advance power-aware processing technology.

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Technology to Convert, Concentrate, or Dry Oil-Based Emulsions, Dispersions, or Liquids Into a Dry Powder Form

A company supplies a variety of chemicals, including inverse emulsions that consist of a very-high-molecular weight, water-soluble polymer dispersed in a continuous oil phase. The typical ratio of the key components is approximately 1:1:1 (polymer:water:oil). The company seeks to convert these emulsions to a water-soluble, powdered form, without losing any of the polymer properties. The problem is particularly difficult due to the oil in the emulsion. The oil is an aliphatic hydrocarbon with a low vapor pressure (0.023 kPa at 20ºC) and a distillation temperature of 255ºC. Respond to this TechNeed at: www.techbriefs.com/tn/200902d.html Email: nasatech@yet2.com Phone: 781-972-0600

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Delivery System to Modify Release of Organic Agricultural Compound

A company’s current product is applied in granular or prill form, and a coating acts to inhibit the release of the product within. The company is looking for a method to modify the release of the organic compound. The compound becomes active when it comes into contact with external reagents in the area of application. Moisture, pH, temperature, and soil types are the influencers. The solution may come in the form of encapsulation, a barrier method, or a novel mechanism that modifies the release rate of the product in granular or prill form. Respond to this TechNeed at: www.techbriefs.com/tn/200902c.html Email: nasatech@yet2.com Phone: 781-972-0600

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NASA Geostationary Coastal and Air Pollution Monitoring

The Geostationary Coastal and Air Pollution Events (GEO-CAPE) mission has been recommended for launch in the 2013-2016 time frame by the National Research Council. The mission’s purpose is to gather science that identifies human versus natural sources of aerosols and ozone precursors, tracks air pollution transport, and studies the dynamics of coastal ecosystems, river plumes, and tidal fronts.

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