About

Gretar Tryggvason is the Charles A. Miller, Jr. Distinguished Professor in mechanical engineering and head of the Department of Mechanical Engineering at Johns Hopkins University. He is widely recognized for his contributions to computational fluid dynamics, including the development of methods for computations of multiphase flows and pioneering direct numerical simulations of such flows. His research areas include computations of multiphase flows, heat transfer, boiling, cavitation, solidification, surfactants, and reactions, with applications to turbulent bubbly flows, atomization, additive manufacturing, and other problems. Tryggvason has also worked on numerical methods for tracking sharp fluid interfaces, averaged and reduced order models of multiphase flows, and multiscale approaches to capture small-scales in multiphase flows.

Research topics

• Computer Science
• Mechanics
• Physics
• Simulation
• Computational science
• Geology
• Parallel computing
• Thermodynamics
• Classical mechanics

Selected publications

• Rise of a confined bubble in a wedge

  International Journal of Multiphase Flow · 2026-01-22

  articleOpen access
  PublisherDOI

• Abstract 4373 A common structural motif mediates dimerization during activation across the human kinome

  Journal of Biological Chemistry · 2026-05-01

  articleOpen access
  PublisherDOI

• Capture of hydrophobic particles by freely rising buoyant bubbles

  Physics of Fluids · 2025-08-01

  articleSenior author

  Buoyant bubbles rising through a suspension of particles can remove hydrophobic particles and carry them upward, leaving hydrophilic particles in the slurry. Here, the passage of a layer of buoyant bubbles through a suspension of hydrophobic particles is examined using fully resolved numerical simulations. Particles colliding with the bubbles are attached, using a simple attachment model. The particles move into the bubble until the contact angle of the triple line is equal to the static angle and slide toward the back of the bubbles, where they accumulate and reduce the rise velocity of the bubbles due to their weight. The passage of the bubbles reduces the volume fraction of the freely suspended particles, as the captured particles are carried upward with the bubbles. A simple averaged drift flux model is introduced to model the rise of the bubbles and their scavenging of hydrophobic particles, and it is shown that relatively simple closure models capture the evolution reasonably well.

  PublisherDOI

• Tethered undersea kite turbine for tidal energy harvesting: A numerical design study

  Renewable Energy · 2025-08-14

  article
  PublisherDOI

• Exact computation of the color function for triangular element interfaces

  arXiv (Cornell University) · 2025-01-08

  preprintOpen access

  The calculation of the volume enclosed by curved surfaces discretized into triangular elements, and a cube is of great importance in different domains, such as computer graphics and multiphase flow simulations. We propose a robust algorithm, the Front2VOF (F2V) algorithm, to address this problem. The F2V algorithm consists of two main steps. First, it identifies the polygons within the cube by segmenting the triangular elements on the surface, retaining only the portions inside the cube boundaries. Second, it computes the volume enclosed by these polygons in combination with the cube faces. To validate the algorithm's accuracy and robustness, we tested it using a range of synthetic configurations with known analytical solutions.

  PublisherOA PDFDOI

• Editorial on machine learning for multiphase flow

  International Journal of Multiphase Flow · 2025-04-22

  article
  PublisherDOI

• Bubbles and bubbly flows

  International Journal of Multiphase Flow · 2025-04-30 · 23 citations

  articleOpen access

  Bubbles and bubbly flows are omnipresent in nature and technology, showing a multitude of phenomena, which can be either beneficial or a hindrance. In any case, for their control and their applications, it is crucial to understand their fundamentals and therefore from the very beginning of the International Journal of Multiphase Flow they have been central. In this synoptic review we give some examples for the fascinating fluid dynamics of bubbles and bubbly flows, starting from their nucleation and cavitation phenomena, then going to single bubble phenomena, and finally to bubbly flows, in which the collective effects of bubbles are key, and to mass transfer in such bubbly flows. The review ends with an outlook on future direction and open issues in the research on bubbles and bubbly flows.

  PublisherDOI

• A front-tracking study of retinal detachment treatment by magnetic drop targeting

  arXiv (Cornell University) · 2025-12-27

  preprintOpen access

  We investigate the Ferrofluid Drop Targeting (FDT) for the treatment of the Retinal Detachment (RD), considering, for the first time, the real 3D geometry of an eye and magnets configurations as well as the viscoelastic rheology of the medium, i.e., the Vitreous Humor (VH). A Front-Tracking Method (FTM) is extended to handle a general 3D unstructured Eulerian grid and strong wall effects. The challenges include the accuracy and robustness of the solver when the drop spreads on the retina under the effect of a magnetic field, which necessitates the design of a multi-region Eulerian grid and defining a threshold distance between the front and wall, along with the choice of an effective front smoothing and volume correction FTM sub-algorithms near the walls. After model validations, the effect of different design parameters on important objectives, such as the travel time, settling time, retinal coverage area, and impact compressive stress, are studied. The results reveal that, in addition to the magnetic Bond number, the ratio of the drop-to-VH magnetic permeabilities plays a key role in the terminal shape parameters, like the retinal coverage. Additionally, simultaneously increasing these two parameters, significantly increase the total FDT force, coverage area, and stress concentration, while decreasing the drop-VH surface tension can mitigate the stress concentration on the retina.

  PublisherDOI

• The Social Outcomes of Participating in the FIRST Robotics Competition Community

  2025-04-02 · 1 citations

  articleOpen access

  Worcester Polytechnic Institute (WPI) and FIRST are partnering to investigate social networking within the FIRST community.FIRST aims to get young people interested in science, engineering and technology by providing young people with opportunities to develop and apply knowledge and skills in science, engineering, and technology.Moreover, FIRST provides a platform for young people to work with one another, work with mentors, and also cooperate and compete with one another.By providing this platform, FIRST encourages participants to develop communication and leadership skills, and may also boost self-esteem and self-confidence in participants.However, the social outcomes of participating in FIRST (e.g., boosts in self-esteem) has yet to be explored. Why Are Social Outcomes Important?According to Erik Erikson's (1959) psychosocial development theory, those between 13-19 are struggling with the question of who they are and what they want to do with their lives (1).Erikson argues that teenagers battle between role confusion (trying to figure out what role they should play) and identity (developing a sense of who they are and what they want to do with their lives).Moreover, Harris (1998) argues that youth are more likely to identify with their peers than their parents, and that peers are more likely to shape behaviors of individuals than parents (2).Thus, teenagers can be highly influenced by their surrounding peers, and it is possible that participating in FIRST may lead to positive benefits in terms of their psychosocial development as their participation may help teenagers find like-minded peers and help them develop an identity.Research also shows that youth who get involved in community programs and consequently interact with other youth and have adult mentors have more positive and advanced developmental outcomes (3,4,5,6).And, self-esteem may be influenced by peers and activities (7). Current ResearchThus, the specific goals of the current project are to (1) investigate social networking in FIRST, (2) investigate the social benefits of participating in FIRST (e.g., increased self-esteem, social awareness, social networking, social skills, etc.), (3) evaluate the usability and effectiveness of different networking and information repository websites that can by used by FIRST participants to better understand what resources FIRST participants are using and why.

  PublisherOA PDFDOI

• Simulations and Modeling of Multiphase Flows

  Proceedings of the World Congress on Momentum, Heat and Mass Transfer · 2025-04-01

  articleOpen access1st authorCorresponding

  Direct numerical simulations of multiphase flows, where every continuum temporal and spatial scale are fully resolved, are now relatively routine, at least for relatively simple disperse flows of bubbles, drops and solid particles, and we show a few examples.The challenges now are twofold: How to use the results to increase our ability to predict industrial scale flows and how to conduct direct numerical simulations of much more complex systems.For predictions, we need coarse models that describe the dynamics of the large-scale flow and in many cases the presence of a sharp phase boundary is the most important feature of the flow.We discuss formal ways to coarsen results from fully resolved simulations while preserving a sharp, but simplified phase boundary.We describe efforts to predict evolution of the coarse flow using machine learning combined with trajectory modeling, where the conservation equations are augmented in such a way that the coarse flow evolves correctly.We also discuss briefly efforts to simulate complex flows, including three-phase liquid-gas-solid disperse flows where the solid particles are either hydrophobic or hydrophilic.

  PublisherDOI

Recent grants

• Multiscale Simulations of Multiphase Flows

  NSF · $339k · 2013–2017

• CDS&E: Collaborative Research: Fast Numerical Simulations of Low Void Fraction Disperse Multiphase Systems using Event-Triggered Communication

  NSF · $239k · 2020–2023

• Multiscale Simulations of Multiphase Flows

  NSF · $277k · 2011–2014

• Multiscale Simulations of Multiphase Systems

  NSF · $40k · 2005–2006

• Selectivity in Froth Flotation

  NSF · $406k · 2021–2023

Frequent coauthors

• Jiacai Lu

  128 shared

• Stéphane Zaleski

  Sorbonne Université

  54 shared

• Asghar Esmaeeli

  Southern Illinois University Carbondale

  32 shared

• Bernard Bunner

  22 shared

• Ruben Scardovelli

  University of Bologna

  22 shared

• Werner J. A. Dahm

  Arizona State University

  21 shared

• Shunji Homma

  Saitama University

  19 shared

• Yue Ling

  Baylor University

  18 shared

Awards & honors

• Charles A. Miller, Jr. Distinguished Professor