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The NASA STI Program Office . . . in Profile

Since its founding, NASA has been dedicated to the advancement of aeronautics and space science. The NASA Scientific and Technical Information (STI) Program Office plays a key part in helping NASA maintain this important role.

The NASA STI Program Office is operated by Langley Research Center, the Lead Center for NASA's scientific and technical information. The NASA STI Program Office provides access to the NASA STI Database, the largest collection of aeronautical and space science STI in the world. The Program Office is also NASA's institutional mechanism for disseminating the results of its research and development activities. These results are published by NASA in the NASA STI Report Series, which includes the following report types:

  • TECHNICAL PUBLICATION. Reports of completed research or a major significant phase of research that present the results of NASA programs and include extensive data or theoretical analysis. Includes compilations of significant scientific and technical data and information deemed to be of continuing reference value. NASA's counterpart of peer-reviewed formal professional papers but has less stringent limitations on manuscript length and extent of graphic presentations.

  • TECHNICAL MEMORANDUM. Scientific and technical findings that are preliminary or of specialized interest, e.g., quick release reports, working papers, and bibliographies that contain minimal annotation. Does not contain extensive analysis.

  • CONTRACTOR REPORT. Scientific and technical findings by NASA-sponsored contractors and grantees.

  • CONFERENCE PUBLICATION. Collected papers from scientific and technical conferences, symposia, seminars, or other meetings sponsored or cosponsored by NASA.

  • SPECIAL PUBLICATION. Scientific, technical, or historical information from NASA programs, projects, and missions, often concerned with subjects having substantial public interest.

  • TECHNICAL TRANSLATION. English-language translations of foreign scientific and technical material pertinent to NASA's mission.

Specialized services that complement the STI Program Office's diverse offerings include creating custom thesauri, building customized data bases, organizing and publishing research results . . . even providing videos.

For more information about the NASA STI Program Office, see the following:

  • Access the NASA STI Program Home Page at http://www.sti.nasa.gov

  • E-mail your question via the Internet to help@sti.nasa.gov

  • Fax your question to the NASA Access Help Desk at (301)621-0134

  • Telephone the NASA Access Help Desk at (301) 621-0390

  • Write to:
    NASA Access Help Desk
    NASA Center for AeroSpace Information
    7121 Standard Drive
    Hanover, MD 21076


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EFFECTS OF SPACE ENVIRONMENT ON FLOW AND CONCENTRATION DURING DIRECTIONAL SOLIDIFICATION

C. Benjapiyaporn, V. Timchenko, E. Leonardi and G. de Vahl Davis
The University of New South Wales, Sydney NSW, Australia

H. C. de Groh III
NASA Glenn Research Center, Cleveland OH, USA


ABSTRACT

A study of directional solidification of a weak binary alloy (specifically, Bi - 1 at% Sn) based on the fixed grid single domain approach is being undertaken.  The enthalpy method is used to solve for the temperature field over the computational domain including both the solid and liquid phases;  latent heat evolution is treated with the aid of an effective specific heat coefficient.  A source term accounting for the release of solute into the liquid during solidification has been incorporated into the solute transport equation.  The vorticity-stream function formulation is used to describe thermo-solutal convection in the liquid region.

In this paper we numerically investigate the effects of g-jitter on directional solidification.  A background gravity of 1 mg has been assumed, and new results for the effects of periodic disturbances over a range of amplitudes and frequencies on solute field and segregation have been presented.


ABSTRACT

 1. INTRODUCTION

 2. MATHEMATICAL FORMULATION

 3. NUMERICAL METHOD

 4. VALIDATION

 5. RESULTS AND DISCUSSION

 6. CONCLUSIONS

 7. ACKNOWLEDGMENTS

REFERENCES



  NASA/TM-2000-209293