Details of the 11th Challenge


Building off of the 10th Challenge, the 11th Industrial Fluid Properties Simulation Challenge will test the capability of molecular dynamics simulation to predict the temperature dependence of viscosity at elevated pressure.



  • November 2018: challenge problem announced
  • October 14, 2019: challenge final entries due
  • November 2019: challenge champions announced at the AIChE Annual Meeting



Dr. Scott Bair (Georgia Tech) has characterized the viscosity of 1,1-diphenyl ethane at elevated pressure and various temperatures.

Entrants are challenged to predict the viscosity at the state conditions summarized below. The scoring criteria will emphasize the predictions of the ratio of viscosities measured at the two temperatures for each pressure condition.

Pressure (MPa) T (°C)
600 37.8
600 60
700 37.8
700 60
800 60
800 98.9

The sample composition has been estimated by GC/MS and is summarized as:

Molecule GC/MS Peak Area (%)
1,1-diphenyl ethane 94.1
diphenyl methanol 2.0
diphenyl methane 0.8
1,1-diphenyl ethanol 0.6
stilbene 0.5
other impurities that are
individually < 0.4 %

Entrants may take this information into account (or neglect it) to whatever extent they deem to be warranted.


Challenge Scoring

Details TBA, but the emphasis will be on predicting the ratio of viscosities measured at the two temperatures for each pressure condition.


Rules of the Game

  • Any theory/modeling/simulation method can be used as long as it is generally accepted to be a “molecular modeling” approach. For example, strictly empirical correlation will not be considered for the challenge. This is in keeping with the focus and goals of the IFPSC to benchmark and promote molecular modeling and simulation methods. If you are unsure whether or not your method is considered to be “molecular modeling” by the challenge organizers, please ask in advance.
  • Any force field (or other model parameterization) previously published in the open literature prior to the announcement of this challenge is acceptable.
  • Force fields (or other models) that have not been published previously may not be parameterized for this challenge using viscosity data for the same molecule at any pressure above atmospheric. Force fields (or other models) may be parameterized using any other published physical property data.
  • Estimates of the uncertainty for the predicted properties must be included.


Other Entry Guidelines

  • Entries are to be submitted to contest[at]ifpsc[dot]org on or before the deadline
  • A submission for this challenge problem is to be in the form of a manuscript suitable for submission to a refereed, archival, scientific journal. The manuscript must contain sufficient detail about the simulation or other method and about the force field (if simulation) so that an experienced simulator could reproduce the results without requiring access to proprietary information. In particular, all potential parameters and molecule geometry parameters must be explicitly specified in the manuscript.
  • An analysis of the uncertainty in the calculated results is required and must be included in the manuscript.
  • Entries are expected to present results that are statistically significant and to present sufficient supporting evidence to establish this quality. Also, the scientific reasoning behind any new (unpublished) force field parameterizations must be clearly spelled out in the entry. If there is a consensus among the judges that an entry is of poor quality (uses a method commonly accepted to be fundamentally flawed, presents results that are not statistically significant, fails to provide sufficient supporting data and details, violates the various rules and guidelines established for the competition, or for any other reason would be unlikely to be accepted by any peer-reviewed scientific journal in the field), that entry will be rejected and will not be considered in the judging.
  • Entries that represent collaborations between multiple research groups are welcomed.


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