Articles on Computer Predictions of Fluid Flow Result in Flood of Queries to ILASL for Advice on Application to Specific Problems and Projects
Figure 1 is a representation of the flow of water under a sluice gate, calculated by John Shannon of T-3 and photographed from the high speed print out system of a LASL computer. Note the major forward wave plus a slight wave that breaks toward the back.
Dear Sir: Our institute is concerned with the study of snow avalanches .... [and] the investigation of natural snow avalanches is restricted to mere observation (with quite a bit of luck), and it requires an extensive logistic support. Therefore, I believe that the most rewarding approach would be computer experiments. However, I would appreciate to have your opinion on this subject as you have already a lot of experience in the field.
This letter, from Dr C Jaccard of the Swiss Federal Institute for Snow and Avalanche Research, is typical of hundreds received by Frank Harlow, T-3 Group Leader, during the past year. The queries have resulted from two articles in Science and Scientific American written by personnel of T-8 (a fluid dynamics theory group at LASL). The articles explained two completely new computer techniques developed by T-3 for the numerical solution of problems in fluid dynamics, techniques that are particularly applicable to studies of waves and other phenomena in the motion of fluids. Examples are the generation of air currents near a cold window, the flow of water from a broken dam, generation of water waves from an explosion, and formation of breakers on a beach.
Of particular interest to most people, the letters indicate, is the fact that in many cases a physical experiment is more complicated and costly and does not provide as much information as a computer experiment.
Group T-3 receives three or four queries per day, and the group members answer all letters. They tell the inquirer whether the problem is computable by any of the T-3 techniques, explain that the LASL group is not generally in a position to take on a project, and that T-3 is willing to talk with representatives from firms or laboratories about their problems. A number of serious outsiders have already taken advantage of this invitation and have come to LASL to discuss specific projects. T-8 welcomes queries, many of which ask extremely provocative questions which help the group with practical applications of the program. Harlow explains that T-3 exists to develop computer techniques, carry out laboratory applications of these techniques, and to make pilot studies to show the scope of what can be done with them, particularly since T3 and the Laboratory have a responsibility to the scientific community and the public as a whole.
Eddie Welch's computer code, SPLASH (a computer code name which stands for nothing in particular), has created the most recent interest.
The University of Alaska is interested in using it to simulate the flow of glacial ice.
The Speech Department of the University of Wisconsin sees the possibility of an extensive study of the speech mechanism through computer application by looking at air pressures and air flows within the vocal tract.
A firm in California called long distance to see if the T-3 computer technique was applicable to designing large surf-generating machines which could generate six-foot: waves for surfing enthusiasts.
The University of Oklahoma points out that the program is of considerable interest to safety engineers concerned with storage of potentially hazardous liquid chemicals and gases. The University's question: In the event that the bottom of a large storage tank should fail completely and the entire liquid contents are dumped in a matter of seconds, how high should a surrounding dike be to prevent splashing over the sides when the liquid wave impacts against the dike walls.
A bee keeper in Great Britain received a no answer to his query. He wondered if the T-3 computer program could handle the problem of keeping his bees warm by distributing hot air over the hives through a series of ducts.
The U.S. Fish and Wildlife Service, Bureau of Commercial Fisheries, in Honolulu, believes the LASL program can be adapted to simulate the flow in an eddy stream, such as that which occurs near the Hawaiian Islands.
West Germany's Ernst-Mach Institut has been working with Bart Daly of T-3, through NATO, on bomb shelter shockwave studies.
The National Institute of Health, as well as numerous doctors and veterinarians, is interested in computer studies to calculate the flow of blood through constricted arteries and branching capillaries. Jacob Fromm, of T-3, explains that this is a particularly challenging application since red blood cells become modified in shape in flowing through constrictions in blood vessels.
Navy contractors are interested in using the LASL computer code for ship design, and for harbor breakwater studies. Argonne National Laboratory believes the code is applicable to a large liquid hydrogen bubble chamber that is being built there. Agricultural engineers at Iowa State University have inquired about use of the LASL program to design large scale irrigation projects in an effort to move quantities of water from one place to another through channels and sluice gates. Scientists interested in a new field of computers which use hydraulic rather than electrical switching have already visited T-8, since the LASL program may help solve problems in this field.
Tony Amsden, of T-3 has been carrying out pilot calculations of meteorite penetration of a solid, such as a space vehicle. His PIC technique is being used by a number of laboratories with appropriate high speed computers. Dan Butler, T-3, has been extending the work to include molecular effects in high-speed gases.
And the requests continue to pour in: Southwest Research Institute, San Antonio, Texas; University of Arizona's Institute of Atmospheric Physics; University of Illinois; Department of Oceanography; Oregon State University; University of Cambridge, England; University of California; Purdue University; Bell Telephone Laboratories; Science Digest; New York University, Courant Institute of Mathematical Sciences; U.S. Weather Bureau; Cornell University; IBM; U.S. Army Mathematics Research Center, University of Wisconsin; Air Force Cambridge Research Laboratories, Bedford, Massachusetts; Institute of Animal Genetics, Edinburgh, Scotland; and the American Institute of Physics, to name a few.
Harlow said the whole T-3 group has contributed to the computer flow studies, and members of the group have presented 21 talks this year. Fromm recently completed a speaking engagement in Europe; C W Hirt will make a presentation of NATO's AGARD (Advisory Group for Aerospace Research and Development) so European scientists can become familiar with the LASL computer code and its applications to fluid dynamics; Eddie Welch has just finished a tour of talks in New York and Massachusetts; Bart Daly will give an invited paper in Los Angeles in February; and Richard Gentry gave an invited paper at the summer APS meeting in Honolulu.
Results from LASL computer codes can be photographed directly from a high speed print out system, giving a motion picture which for all the world looks like the actual thing - a dam breaking, a sluice gate opening, or the flow of liquid around a stationary object, whether it be a rock or the Hawaiian Islands. The detailed comparisons show that the results are quite accurate representations of actual events.
Daly and Hirt, through D-8 and D-10, recently put together such a motion picture, which is in continuous demand for showings, and a French scientist recently suggested the movie be entered in the International Film Festival at Cannes.