Summaries of LFTE Panel Workshops

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Workshop Attendee Addresses

September 17-18, 1996 Attendees | Agenda | Summary

November 12-11, 1996 Attendees | Agenda | Summary

February 25-26, 1997 Attendees | Agenda | Summary

April 29-30, 1997 Attendees | Agenda | Summary

June 24-25 1997 Attendees | Agenda | Summary

August 26-27, 1997 Attendees | Agenda | Summary

February 24, 1998 Attendees | Agenda | Summary

September 17-18, 1996

This First Workshop was devoted to identifying the state of the art for physics-based models as applied to both vulnerability and lethality of engagements happening above the surface of the water. The briefings concerned hydrocodes almost exclusively. The attendees and agenda are listed elsewhere on this site. If you wish to have a copy of any briefing, please contact the briefer directly.

At the end of the Workshop, we collected a list of upgrades that the attendees identified as needed to continue to develop the codes and meet upcoming needs. In no particular order, these items are listed here:

In addition, the Test and Evaluation community representatives provided feedback comments both at the meeting and through their written evaluations. A compilation of their comments is listed below.

Several action items resulted from this meeting.

  1. There should be at least one follow on meeting to continue the discussion.
  2. TEREC will publish the results of the Workshop on its Web site.
  3. TEREC will establish a model repository on its Web site for these models.

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November 12-13, 1996

This Second Workshop was devoted to identifying the state of the art for physics-based models as applied to both vulnerability and lethality of engagements happening above the surface of the water and was a follow on to the earlier meeting of September 17-18, 1996. The briefings were not exclusively concerned with hydrocodes and included not only other kinds of physics-based models but also included information about some specific Test and Evaluation (T&E) applications. The attendees and agenda are listed elsewhere on this site. If you wish to have a copy of any briefing, please contact the briefer directly.

One of the results of the meeting was a Pareto vote by the attendees on the upgrade options obtained at the First Workshop. Additions were welcomed, and one, simulations of stochastic phenomena, was added. The results of the vote were interpreted in four categories, which are listed below in their order of priority:

  1. Model Upgrades
  2. Input Improvements
  3. Validation
  4. Infrastructure

Model Upgrades

The model upgrades list in order of priority is shown below:

  1. Coupled effects
  2. Non-ideal explosives
  3. Full system modeling
  4. Simulation of stochastic phenomena
  5. Multiple effects
  6. Time scaling
  7. Length scaling

Generally these show a movement toward expanding the realism and scope of the applications. The applications that were briefed, two lethality problems and one survivability problem, were ones that could profit from the higher priority items on this list.

Input Improvements

The input improvements are listed below in order of priority:

  1. Better failure models
  2. Better fragment field characterization

The first item was taken by many of the participants to include not only failure modeling, but also materials properties and equations of state, etc. We will henceforward include these explicitly and lump them together. The materials that have been specifically mentioned are concrete and composites. The first item was also the overall highest priority item of all the individual items in the voting.

Validation

The validation items, validation criteria and physical benchmarks, were equal in priority. They were tied with the highest item under Model Upgrades.

The issue of validation is a most important one for future applications of these models to T&E problems, not only because the Department of Defense (DOD) T&E directives require that models and simulations for T&E be validated, but also because publicized validation can improve the community perception of these models. The issue of validation criteria, however, will depend upon the application, specifically the risk that a decision maker is willing to accept.

The physical benchmarks were discussed as a kind of data base for model output comparisons. There was some discussion about the required breadth of these data bases, having to range across both lethality and vulnerability as well as across many different physical conditions, including detailed time evolution data. A suggestion was made by Greg Czarnecki that SURVIAC might be an appropriate repository for some of these data bases.

Infrastructure

The three items in this group, in order of decreasing priority, were:

  1. Better computers
  2. Revised code architectures
  3. Runtime analyst-in-the-loop capability

This group overall ranked lowest, probably not because it was less important than the others but more likely because it is somewhat outside the scope of the Panel to influence. Two briefings at the Workshop covered planned capabilities by the Department of Energy (DOE) ASCI and DOD HPCM programs that are addressing these issues already. The DOE-DOD MOU, which was also briefed, provides a method of funding the DOE laboratories to revise code architectures, potentially including the analyst-in-the-loop capability. The improved infrastructure that these efforts represent could make current capabilities better as well as improve future applications and upgrades.

Another Poll

In addition to the general Pareto voting above, three of the briefers who concerned themselves with specific applications, were privately polled about their needs and priorities. This list, including the number of votes for each item, is included here:

In addition, one voter added a materials problem to the concrete and composites listed earlier:

Although this poll has poor statistics, it shows a distinct bias toward practical, every-day issues, as you might expect from practitioners embroiled in real world problems.

Summary

Voting is not science or engineering. However, the polls do contain some of the expert opinions of current workers in the field, and were a quick way to try to capture that expertise. Further facts and analyses are needed as well. In addition, the Workshop scope has not yet included the underwater and water surface effects that will be the subject of the next Panel Workshop.

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February 25-26, 1997

The focus of the Third Workshop switched to underwater explosion and effects modeling for vulnerability and lethality. The briefings again were mostly concerned with hydrocodes, although other kinds of physics-based models were also discussed. The attendees and agenda are listed elsewhere on this site. If you wish to have a copy of any briefing, please contact the briefer directly.

The panel objectives remain to determine the state of the art and to identify future needs for physics-based models to support T&E, particularly Live Fire T&E. The needs identified in the first and second workshops were evaluated by the attendees at this workshop for pertinence to underwater explosions. The issue of damping was added to the list and it was taken to be an input parameter, meaning that the physical parameters of damping for normal modes of the system is the issue, rather than new and better models of damping itself. Given that the hydrocodes remain the major subject of discussion, it is not surprising that the changes were small. Indeed, all items from the first and second workshops elicited some support in the Pareto voting that occurred at the end of this third workshop.

The voting provided the same order of overall priorities by general category:

  1. Model Upgrades
  2. Input Improvements
  3. Validation
  4. Infrastructure

None of these general categories was very low in priority. The overall per item weights showed these areas as the first four, which includes one from each of the general categories:

Within each general category, there were some significant changes from the second workshop results. These appear generally to related to the change in subject matter.

Model Upgrades

The model upgrades in order of priority are these:

These bear some relation to the results of the previous workshop. Scaling issues rank last on both priority lists. The changes in priority might be related to the changes in subject matter, which will be analyzed later.

Input Improvements

The priority for the input improvements was:

  1. Better material and failure models
  2. Damping
  3. Fragmentation field characterizations

These results clearly demonstrate a subject matter effect. Fragmentation is important to fragmentation warheads and behind-armor spall modeling, both of which were rarely mentioned in this workshop. The spread here is immense. Better materials and failure models here rank above the highest item in model upgrades, while the fragmentation issue has only half the priority of the lowest ranked model upgrade.

Validation

Validation continues to rank third. The issues in priority were:

  1. Physical benchmarks
  2. Validation criteria

The underwater community has the UNDEX database that is available through NSWC/UERD. The single point of contact that this implies is not available for the above-the-water community, although there the variety of systems and materials may be more extensive.

Infrastructure

These three issues in order of priority were:

  1. Revised code architectures
  2. Analyst in the loop
  3. Better computers

This is the reverse of the priorities of the last workshop, but probably displays the knowledge that most infrastructure improvements in the area of better computers are somewhat beyond the scope of the workshop to influence. However, all participants agreed that better computers would enhance their work and permit such improvements as brute-force solutions to the scaling problems.

This workshop completes our currently planned meetings on physics-based modeling of ballistic weapons (although others are not out of the question). A summary of the results to date for all three workshops will be posted on this web site. This will include a definition of the scope of each of the items we have been prioritizing and a discussion of the differences between the above the surface and below the surface workshops, with implications for our goals of determining the current state of the art and outlining future steps to enhance the models applicability to Live Fire T&E.

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April 29-30, 1997

The Fourth Workshop of the Live Fire Test and Evaluation Panel on Physics-Based Models was held at Southwest Research Institute in San Antonio, Texas on 29-30 April 1997. The agenda and attendees list are posted elsewhere on this site. Please contact briefers directly for copies of their charts.

The focus of this workshop was on fire. Participants included fire modelers, fire testers, and T&E and program personnel with interests in these areas. Both vulnerability and lethality communities were represented.

Several kinds of models were briefed. These ranged in detail and sophistication from zone models of smoke and fire spread in compartmented structures such as buildings and ships to CFD calculations of the flow fields in engine nacelles. To some extent, the issue revolves around the quantization of the geometry. Zone models break down each compartment volume into two sub-volumes called zones, an upper one and a lower one with a variable boundary height. More detailed models perform calculations with 10,000 or more sub-volumes. These models are generally limited to the effects of fire and not fire itself. They sometimes assume a constant fire source and model smoke and temperature changes.

Following a workshop tradition, we built a prioritized list of needs in fire modeling. An initial list was abstracted from the first day’s briefing charts, and extended and refined on the second day. Pareto voting resulted in the list below. These clumped naturally into four bins of nearly equal votes, which means here that each group member has about twice the weight of the members of the next lower group. Votes for the lowest group ranged from 0 to 4.

Prioritized list of Modeling Needs

  1. Validation Data and Processes
    Materials Models
  2. Models of Fire Itself (not just fire effects)
    V/L Architecture/Methodology
    Coupled Effects
    Fire Suppression Modeling
    Uncertainty Analysis, including Identification of Largest Uncertainties
  3. Stochastic Phenomena
    Non-Linear Phenomena
  4. Dimension Scaling
    Cheaper, Better and Faster Computers
    New Codes
    Visualization of Outputs
    More Efficient Algorithms
    Time Scaling
    Predictive
    Standard Test Procedures

If we collapse these into our previous categories, we obtain this prioritized list of general categories:

  1. Model Upgrades
  2. Validation
  3. Input Improvements
  4. Infrastructure

This list has no place for the V/L architecture/methodology/approach or predictive tools issues, although just these together would rank at the level of Input Improvements on this list. The reason these were stripped from the list has to do with the exclusion of comments from the T&E community at the first workshop. There, T&E personnel (attendees with no particular knowledge of physics-based models but with significant potential applications and knowledge of T&E) were separately polled on their issues with the modeling and simulation technologies briefed in Workshop I. These comments in general probably follow from the distinct histories of the models and their application regimes. The attendees developed a set of examples to display a range of potential responses to the expressed DOD needs. These examples were selected to include support for upcoming tests of a range of systems on the LFT&E oversight list, systems whose analysis will not be data limited, and analyses that include both the fire and ballistic modeling. Some features of these sample topics are indicated below.

  1. F-22 Example
    The objective of this analysis is to develop and demonstrate a cost effective method for modeling engine nacelle fire suppression. Two typical models might be VULCAN and KIVA, and the analysis could use data and extend methods developed earlier for the F-18. It would deal with priorities of Validation and Fire suppression modeling issues from this workshop.
  2. SC21 Example
    The objective of this analysis is to show the coupled effects of ballistic damage and fire, since the geometry of the penetration holes will drive the dynamics of the fire. It will also be possible to compare the results of two methods of modeling fire: zone and field models. Two models for potential application are SVM and CFAST, and pertinent data appear to be available from JLF tests. This example would deal with the Coupled Effects and Validation issues from the priorities lists of this and previous workshops.
  3. Theater Missile Defense
    The objective of this task is to bring first principles models to bear credibly in an area where direct tests are impossible. Potential models include CTH and SPH approaches, with data available from sled tests and gas guns. This example deals with the Validation issues from previous workshops and relates directly to the next workshop to be held at Los Alamos in June.

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June 24-25, 1997

The Fifth Workshop of the LFTE Panel on Physics-Based Models met at the Los Alamos National Laboratory on June 24-25, 1997. The attendees list and agenda are available elsewhere on this web site. The technical subject was hypervelocity impact modeling, but the agenda included discussions of the demonstration tasks that were initiated at Workshop IV and elaborated at the June 3 meeting at Aberdeen Proving Ground, Maryland.

Hypervelocity Impacts

The hypervelocity impact problem offers a significant example of physics-based models applied to LFT&E. Direct tests in the kinematic region of interest are not possible, making modeling with extensive extrapolation to the region of interest the only possible mechanism for determining lethality in operational conditions. An additional feature is the relative familiarity of the missile and space communities with modeling. So many effects have been inaccessible by testing in these areas that modeling is a commonly accepted tool for many programs.

Hypervelocity impact modeling efforts are a strong part of the physics-based modeling and simulation programs at the national laboratories. Growing from the nuclear mission of the labs, the need to perform these kinds of calculation has led the labs to develop significant expertise in hydrocodes and the capability to implement them for many real world problems. The expertise to develop and operate these codes is relatively scarce outside the labs, although both Kaman and New Mexico Tech provided evidence of some serious modeling programs in this area outside the DOE labs. The data collection efforts to support validation of the codes by Holloman High Speed Test Track and Arnold Engineering Development Center gas guns were also briefed.

One special feature of this program was the briefing by Glenn Pomykal of Lawrence Livermore National Laboratory, who represented the National Missile Defense program. Dr. Pomykal briefed programs of the NMD/DOT&E Hydrocode Initiative, an effort related in subject matter to this Fifth Panel workshop. Dr. Pomykal is awaiting approval of his briefing for release, at which point it will be available for distribution.

The workshop differed from previous Panel efforts in several other ways. It did not include the usual diversity of communities. Because of military force asymmetries, the only interested communities are those concerned with lethality. The national laboratory components were present in an unusually strong plurality, due partly to the meeting location and partly to the interest in briefing several technically diverse areas from several of the labs.

The workshop also did not follow the traditional mechanism of developing a prioritized list of needed enhancements. Several briefings did list some needs, and there was general agreement on the items, in that no one suggested that an item needed to be removed. The list is reproduced here. The development of the demonstration tasks was seen by the workshop as making prioritization of these enhancements unnecessary. The enhancements that will be implemented will be those that are required for the demonstration tasks. The utility of the tasks and their outputs will be sufficient justification and prioritization for the specific enhancements that are implemented.

Suggested M&S Enhancements for Hypervelocity Impacts

Demonstration Tasks

There was a significant discussion of the demonstration tasks. The current list with their proponents is shown below. The proponents are responsible ensuring that details are added to the tasks, and that other members of the Panel participate. Any comments or questions about these tasks should be directed to the proponents.

Demonstration Tasks and Proponents

  1. Hypervelocity Impacts:
    Repa, LANL (to be replaced, perhaps by Weir, SNL)
  2. Shipboard Ballistic Through Fire:
    Couch, LLNL
  3. Engine Nacelle Fire:
    Rondeau, SNL
  4. Standard Fire Test Set:
    Moya, SNL
  5. Hydrodynamic Ram:
    Rondeau, SNL
  6. Missile Solid Propellant Vulnerability:
    Heard, Eglin
  7. Armor Penetration:
    Deitz, ARL

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August 26-27, 1997

The Sixth Workshop of the LFTE Panel on Physics-Based Models met at Sandia National Laboratories on August 26-27, 1997. The attendees list and agenda are available elsewhere on this web site. The technical subject was High Power Microwaves (HPM), but the agenda included breakout sessions and briefings on the demonstration tasks that were initiated earlier. Some breakout groups extended their time together by meeting in parallel sessions during the HPM briefings.

High Power Microwaves

The High Power Microwave briefings occupied most of the first day of the Workshop. They included both experimental results, modeling capabilities, and test results briefings.

The HPM simulations in several areas are directly concerned with physics-based modeling. The steps include the generation and transport of radiation, the coupling of the radiation to the target and within the target to the subsystems and components, and the effects of the radiation on the component/subsystem and the subsequent effect on system mission capability. Modeling these steps can be direct applications of well known physics, and it appears that models of many steps exist and are quite robust. Some of the effects models at the component level are data base driven, rather than modeled from first principles. Like most lethality applications of high fidelity physics-based models, making the final move from component interactions to effects on system mission capability requires another step outside the physics-based model environment. There was agreement that the modeling of the process from generation of radiation to system effects is now a unfederated set of independent models that can be coupled only with considerable off line effort.

Although the time devoted to briefings was abbreviated compared to other workshops, the workshop briefing charts did include suggested improvements, which were abstracted and are reproduced here with no attempt made to prioritize the list. These suggestions, like those of earlier workshops, can be divided into the categories of improved inputs, code enhancements, VV&A, and infrastructure improvements.

Suggested M&S Enhancements for High Power Microwaves

Demonstration Tasks

There was a significant discussion of the demonstration tasks. Interested parties met in breakout sessions for each of the demonstration tasks. The tasks were briefed at a closing plenary session of the Workshop after the breakout sessions were completed. A summary of the tasks is provided in the list below, in the order of debriefings.

  1. Propellant Reactivity
    Briefed by Mike Heard, Chicken Little, Eglin AFB, FL
    Issue: Can propellant reactivity be modeled using physics-based codes sufficient for LFTE applications?
  2. HPM #1
    Briefed by Mark Henderson, NAWCWPNS, China Lake. CA
    Issue: Improve HPM Modeling of system upsets using AH1-S testbed for extrapolation to AH1-W.
  3. HPM#2
    Briefed by Pat Vail, AFRL, Kirtland AFB, NM
    Issue: Predicting the fields and mode structure in a building is a problem which exceeds the capabilities of current codes, especially for wide-band and non-uniform illumination.
  4. Missile Defense
    Briefed by Bob Weir, Sandia National Laboratories, Albuquerque, NM
    Issue: Develop a modeling and simulation approach to supplement tests in defining the lethality envelope for BMD fragmenting/hit-to-kill missiles/warheads.
  5. Fire Suppression
    Briefed by Dan Rondeau, Sandia National Laboratories, Albuquerque, NM
    Issue: Can modeling and testing be integrated for improved agent transport and fire suppression in aircraft engine nacelles? Can modeling improve fire initiation and suppression evaluations in ground combat vehicles?
  6. Hydrodynamic Ram Modeling Effort
    Briefed by Frank Addessio, Los Alamos National Laboratory, Los Alamos, NM
    Issue: 75% of combat losses are a result of fuel system vulnerability, and HRAM is a significant kill mechanism
  7. Ship Fire Modeling
    Briefed by Ron Reese, IDA, Alexandria, VA
    Issue: Predict fire phenomenology associated with an anti-ship missile explosion in a ship-board compartment

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February 24, 1998

This meeting of the LFTE Panel on Physics-Based Models was held at the Physical Science Laboratory of New Mexico State University in Las Cruces, New Mexico on 24 February 1998. The attendees list and agenda are available elsewhere on this web site. If you have questions about specific briefings, please contact the briefer directly.

Unlike the Panel workshops, there was not a specific technical theme for this meeting. The agenda was devoted to progress updates and to briefings by new attendees. Since the August meeting, the proposed task on fire suppression has begun. Lou Gritzo of Sandia briefed the project plan, which includes participation by AFRL in Dayton and SwRI in San Antonio. The other tasks defined at the August meeting are appropriate vehicles to resolve pertinent T&E issues, but funding for them remains uncertain. Capability and interest briefings were provided for Oak Ridge National Laboratory and Argonne National Laboratory programs as well as the Fire and Smoke modeling effort at Electric Boat.

These workshops were conducted as part of the Live Fire Test and Evaluation Panel on Physics Based Models research project.

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Last Updated December 20, 2007