Research Archive
Simulating Fate and Transport of Expiratory Droplets
Transport and fate of human expiratory droplets play a key role in the transmission of respiratory infectious diseases. The dynamics of virus transmission is not well understood, with one challenge being the complicated fluid and flow characteristics involved in the fate and transport of virus, including source dynamics (e.g., exhale velocity and temperature, droplet sizes, virus load, and droplet–virus correlations), ambient conditions (e.g., mean and turbulent flows, temperature, and humidity), and virus dynamics (e.g., virus viability and infectious rate). Collaborating with experts in influenza virus transmission, we recently developed a fate and transport model to simulate droplet evolution during normal human respiratory activities (talking, coughing, etc.). We improve the model prediction by using a continuous random walk model to better characterize the correlated velocity fluctuations in these respiratory flows.
The simulation shows strong influences of ambient conditions, exhaled velocities and temperatures. The dispersion and evolution of droplets with different initial diameters have very different sensitivity to ambient environments. In the future, we will incorporate the correlation between droplets and viruses to understand the transport of viruses and the risks of exposure at different locations.
Transport and fate of human expiratory droplets play a key role in the transmission of respiratory infectious diseases. The dynamics of virus transmission is not well understood, with one challenge being the complicated fluid and flow characteristics involved in the fate and transport of virus, including source dynamics (e.g., exhale velocity and temperature, droplet sizes, virus load, and droplet–virus correlations), ambient conditions (e.g., mean and turbulent flows, temperature, and humidity), and virus dynamics (e.g., virus viability and infectious rate). Collaborating with experts in influenza virus transmission, we recently developed a fate and transport model to simulate droplet evolution during normal human respiratory activities (talking, coughing, etc.). We improve the model prediction by using a continuous random walk model to better characterize the correlated velocity fluctuations in these respiratory flows.
The simulation shows strong influences of ambient conditions, exhaled velocities and temperatures. The dispersion and evolution of droplets with different initial diameters have very different sensitivity to ambient environments. In the future, we will incorporate the correlation between droplets and viruses to understand the transport of viruses and the risks of exposure at different locations.
Syn-bubbles: Synthesis of the Physical Processes in Subsea Bubble Plumes to Connect Natural Seeps and Oil Spills
In this GoMRI funded project, we seek new understanding of the difference between natural seep bubble plumes and accidental oil spill blowouts. More importantly, the goal of this study is to quantify the connection between them which will help us to better predict the evolution of plumes at different initial conditions. The GoMRI's project site can be found at this link.
The two videos on the left show the differences between natural seep bubble streams (Green Canyon Lease Block 600, Gulf of Mexico) and accidental oil spill plumes during the DeepWater Horizon (DWH) blowout. These two multiphase phenomena have different physical scales (length, velocity, etc.), which describe different stages of multiphase flow regimes.
The third video shows the high speed images of natural emanated hydrocarbon bubbles from the seafloor at a Mississippi Canyon M118 site, where gas hydrate was forming when these bubbles rise from the seafloor. Our project has observed these bubbles in the field, simulated them in laboratory, and modeled them using fate and transport models.
The two videos on the left show the differences between natural seep bubble streams (Green Canyon Lease Block 600, Gulf of Mexico) and accidental oil spill plumes during the DeepWater Horizon (DWH) blowout. These two multiphase phenomena have different physical scales (length, velocity, etc.), which describe different stages of multiphase flow regimes.
The third video shows the high speed images of natural emanated hydrocarbon bubbles from the seafloor at a Mississippi Canyon M118 site, where gas hydrate was forming when these bubbles rise from the seafloor. Our project has observed these bubbles in the field, simulated them in laboratory, and modeled them using fate and transport models.
Multiphase plume generated by the deepwater horizon oil spill
Bubble kinematics of natural hydrocarbon seeps
High-speed video of natural seep bubbles
Observing and Modeling of the Fate and Transport of Natural Seep Bubbles
Transport and fate of the natural seep bubbles are important to oceanic biogeochemistry. The goal of this study is to analyze the observed field data during our previously research cruises in the Gulf of Mexico, as well as the experimental data obtained by the DOE’s National Energy Technology Laboratory (NETL). A corrected hydrocarbon dissolution module was used to predict the dissolution of the methane bubbles rising from ~1,000 m ocean floor. This work is a collaborative effort with Dr. Socolofsky at Texas A&M University. The final report of this project can be found here.
Transport and fate of the natural seep bubbles are important to oceanic biogeochemistry. The goal of this study is to analyze the observed field data during our previously research cruises in the Gulf of Mexico, as well as the experimental data obtained by the DOE’s National Energy Technology Laboratory (NETL). A corrected hydrocarbon dissolution module was used to predict the dissolution of the methane bubbles rising from ~1,000 m ocean floor. This work is a collaborative effort with Dr. Socolofsky at Texas A&M University. The final report of this project can be found here.
Surfacing Bubble Plume and Induced Current
Bubble plume is a common fluid dynamics phenomenon. It exists in both natural and engineered waters. For instance, engineers use bubble plumes to increase dissolve oxygen and mixing level in reservoirs or lakes, known as aeration processes. The rising bubbles entrain water while they rise under the buoyancy force, carrying mass and momentum from ambient fluids. When these bubbles reach surface, the direction of fluxes changes from the vertical to horizontal direction, causing water movement on the surface, known as surface current
The plume induced surface current can spread out the oil during a subsurface oil spill. When surface is covered by ice, the roughness of the ice surface would trap the surfacing oil and change the hydrodynamics of the flow, which also change the spreading of the oil. The goal of this study is to quantify the physical parameters that are related to the spreading process: how the surface velocity would decay away from the origin, and how surface condition would modulate the spreading process.
The plume induced surface current can spread out the oil during a subsurface oil spill. When surface is covered by ice, the roughness of the ice surface would trap the surfacing oil and change the hydrodynamics of the flow, which also change the spreading of the oil. The goal of this study is to quantify the physical parameters that are related to the spreading process: how the surface velocity would decay away from the origin, and how surface condition would modulate the spreading process.