1. Amir Kohanpur

PhD Candidate

Department of Civil and Environmental Engineering

University of Illinois at Urbana-Champaign

UIUC - WRES

Attendance SignIn

Title: Pore-to-core upscaling of flow in heterogeneous porous media

Abstract:

Understanding the physics of flow in natural porous media is essential in many applications such as carbon sequestration in deep saline aquifers, recovery of oil from hydrocarbon reservoirs, contaminant transport, water infiltration in the vadose zone, etc. Current x-ray micro computed tomography scanning technology is able to capture actual pore morphology of rocks and pore-scale modeling can take into account fundamental displacement processes to predict macroscopic properties which are vital in large-scale modeling. Although current pore-network modeling, as a popular pore-scale modeling tool, can predict macroscopic properties with efficient computational costs compare to other tools, most studies are limited to small sample size and core plugs that does not incorporate completely the 3D complexity and heterogeneity of the natural rock. There are also limitations for attaining a large representative pore structure for a heterogeneous core, namely the technical limits on sample size to discern void space and computational limits on pore-network extraction tools. To address these challenges, we introduce a novel pore-network stitching approach that uses fine resolution images of a few “signature” parts of a core to extract local pore-networks, combines their statistics to generate pore-networks throughout the core volume, and then stitch all sections together to obtain a global pore-network. We validate and test the workflow on different types of rocks based on the single-phase and two-phase flow properties of the global stitched pore-network. Our approach provides a large representative pore-network for the entire core and can be applied for other purposes such as reactive transport and mechanical properties as well.

2. Andres Prada

PhD Candidate

Department of Civil and Environmental Engineering

University of Illinois at Urbana-Champaign

UIUC - WRES

Title: Using turbulence as a mechanism to control the spread of grass carp in streams at early-life stages

Abstract:

There is an urgent need to monitor and control the spread of invasive grass carp (Ctenopharyngodon idella) in North America. Grass carp are reproducing in tributaries to Lake Erie and control efforts targeting reproduction are greatly needed. This study examines how early life stage grass carp interact with turbulent flows, how the turbulence affects their survival, and whether turbulence-based control methods could work. An extensive series of laboratory experiments were conducted with live grass carp eggs and larvae in a grid-stirred turbulence tank and in a racetrack flume to: a) explore the effect of turbulence intensity on egg mortality, and b) to document the behavioral response of grass carp larvae to spatially-variable, turbulent flows. Our data identified a turbulence intensity threshold, above which egg mortality substantially increased due to short- (10 seconds) and long-term (5 minutes) exposure at different turbulence levels. Larvae actively responded to changes in turbulence intensity and shear stresses produced by obstructions in the flow (e.g. rocks, piers, and submerged vegetation), avoiding areas of high shear and seeking low-turbulence, low-vorticity regions. This study produced a unique and extensive data set that may allow for the development of turbulence-based control methods for grass carp. Such control methods could include increasing egg mortality by increasing turbulence intensity through temporary and permanent in-river structures or using natural or modified hydrodynamics to attract, guide, and aggregate larvae at predefined control points for collection or extermination.

Biography:

Amir Kohanpur is a Ph.D. candidate in Civil Engineering at the University of Illinois at Urbana-Champaign and working under supervision of Prof. Valocchi. His research focuses on pore-scale modeling of multiphase flows in porous media with the application of geological storage of carbon dioxide. He graduated with a B.Sc. in Mechanical Engineering from Shiraz University in 2011 and a M.Sc. in Mechanical Engineering from Sharif University of Technology in 2013.

Andres is a PhD candidate in the Department of Civil and Environmental Engineering at the University of Illinois at Urbana-Champaign, under the supervision of prof. Rafael Tinoco. During his doctoral studies, he has been conducting hydrodynamic experiments at the Ecohydraulics and Ecomorphodynamics Laboratory with live fish eggs and larvae to investigate the physical processes driving the transport of grass carp in streams at early-life stages. He received his MS in 2016 from the Department of Agricultural and Biological Engineering also at UIUC, and his BS in Civil Engineering from Universidad Industrial de Santander, Colombia in 2013.