<!--![](https://km.fjfi.cvut.cz/_images/head_img_en.png =100%x)--> ![](https://jlk.fjfi.cvut.cz/md/uploads/4861ac29-08d4-4337-add3-b10354dfeb67.jpg =100%x) # Workshop on Environmental Modeling: <br/> Fluid Flow and Transport Phenomena ## June 12, 2024 :::info This event is a collaborative scientific workshop bringing together researchers from the Czech Republic and the United States, featuring __special guests from the [U.S. Army Corps of Engineers (USACE) Engineer Research and Development Center (ERDC)](https://www.erdc.usace.army.mil/)__. The primary aim is to foster international collaboration, share research findings, and discuss advancements in scientific fields of mutual interest, namely __fluid flow, transport mechanisms, phase transitions, and interactions between land and atmosphere__. ::: ## Venue <section style="display: flex; gap: 2em;"> <section style="flex: 0 0 50%;"> <!-- Fakulta jaderná a fyzikálně inženýrská České vysoké učení technické v Praze --> Faculty of Nuclear Sciences and Physical Engineering Czech Technical University in Prague Trojanova 13 120 00 Praha 2 __Lecture hall T-101__ </section> [![](https://jlk.fjfi.cvut.cz/md/uploads/609a3fbc-0aca-4e02-8385-5e524ae92e8c.png)](https://www.openstreetmap.org/node/296630299#map=18/50.07445/14.41773) </section> ## Programme All time slots include the time for discussion (10+ min). | Time | Speaker | Title | |:-----:|---------|-------| | 9:00--9:30 | Dr. Andrew Trautz | [The Power of ERDC](#keynote) | | 9:30--10:00 | Dr. Klára Jurčáková | [Frozen-turbulence hypothesis in wind-tunnel model of atmospheric boundary layer](#frozen-turbulence) | 10:00--10:20 | | _coffee break_ | | 10:20--10:XY | Dr. Matthew Farthing | Monolithic Multiphysics Simulation for Environmental Hydrodynamics | 10:XY--11:20 | Dr. Matthew Farthing | [Model Reduction and Operator Learning for Environmental Flows](#model-reduction) | 11:20--12:00 | Dr. Andrew Trautz | [Simulating the Near-surface Geo-environment to Inform Buried Explosive Threat Detection](#explosive-threat-detection) | | 12:00--13:30 | | _lunch break_ | | 13:45--14:20 | Dr. Pavel Strachota | [Experimental Validation of Multiphase Particle-in-Cell Simulations of Fluidization in a Bubbling Fluidized Bed Combustor](#fluidization) | | 14:20--14:55 | Dr. Orie Cecil | [Examination of Analytical Shear Stress Predictions over Simplified Dunes](#simplified-dunes) | | 14:55--15:10 | | _coffee break_ | | 15:10--15:35 | Dr. Michal Sněhota | [Multi-Layer Constructed Technosol Systems with Different Configurations for Green Roofs: Rhizobox Study Using Open-Source CNC Gardening Robot](#green-roofs) | | 15:35--16:10 | Dr. Andrew Trautz | [Physical modeling of near-surface geo-environments: Overview of the synthetic environment for near-surface sensing and experimentation (SENSE) Research Facility](#sense) | ### Keynote: The Power of ERDC <a id="keynote"/> #### Speaker: Dr. Andrew Trautz __Abstract:__ The U.S. Army Corps of Engineers (USACE) Engineer Research and Development Center (ERDC) is a world-class research and development organization focused on discovering, developing, and delivering trusted engineering and scientific solutions for the warfighter and Nation. This presentation provides a high level overview of the ERDC, history, core competencies and top research priorities. ### Frozen-turbulence hypothesis in wind-tunnel model of atmospheric boundary layer <a id="frozen-turbulence"/> #### Speaker: Dr. Klára Jurčáková __Abstract:__ Although the main assumption of Taylor's frozen-turbulence hypothesis is not met in many boundary layers, it is commonly used to calculate integral length scales from point measurements. Wind tunnel modeling was used to analyze flow in the vicinity of the meteorological observatory Kopisty (CZE). Particle image velocimetry with high temporal resolution (TR-PIV) allowed us to analyze both temporal and spatial correlations in the turbulent flow fields simultaneously and to evaluate the frozen-turbulence hypothesis. The measurements in vertical and horizontal planes reveal that there is a very good agreement between integral length scales based on various methods. ### Model Reduction and Operator Learning for Environmental Flows <a id="model-reduction"/> #### Speaker: Dr. Matthew Farthing __Abstract:__ Complex multiphase flow and transport processes are fundamental to many of the problems being solved by the U.S. Army Corps of Engineers. Incorporating high-fidelity simulations into our engineering workflows remain a challenge with respect to technical expertise and cost (financial and computational). In this presentation we explore projection-based model reduction as a way to still provide accurate predictions but at reduced computational cost. ### Simulating the Near-surface Geo-environment to Inform Buried Explosive Threat Detection <a id="explosive-threat-detection"/> #### Speaker: Dr. Andrew Trautz __Abstract:__ Training automated target recognition algorithms to detect landmines and other buried explosive threats from imagery collected in complex geo-environments remains a significant challenge, necessitating large and diverse datasets that are not always readily available. Physically generating requisite data can be both cost and time prohibitive, thus the growing interest in using synthetic data to supplement existing datasets. To this end, the US Army Engineer Research and Development Center (ERDC) continues to develop a computational test-bed called the VESPA (Virtual Environmental Simulation for Physics-based Analysis) to support synthetic multi-spectral and hyper-spectral EO/IR imagery generation. In this presentation, we provide an overview of the VESPA and its historic use in landmine detection research at the ERDC. ### Experimental Validation of Multiphase Particle-in-Cell Simulations of Fluidization in a Bubbling Fluidized Bed Combustor <a id="fluidization"/> #### Speaker: Dr. Pavel Strachota __Abstract:__ As part of our long-term aim at developing a complex CFD simulation tool for bubbling fluidized bed boilers operating in oxyfuel regime, we have performed several fluidization experiments to validate our numerical algorithm for multiphase flow simulation. The algorithm combines and extends the function of several components of OpenFOAM, using the Multiphase Particle In Cell method within a custom solver derived from coalChemistryFoam. In this contribution, we focus primarily on the design of the experiment, the methodology of data processing, and the obtained results. The experimental device used is a model of the combustion chamber, the distributor, and the windbox. Its transparent walls are made of polymethyl methacrylate. In the experiments, three different materials (sand and two types of LECA suitable for use in fluidized bed combustion) were subjected to fluidization at different flow rates, using air at room temperature as the fluidization medium. The flow rates and the pressure drop at the fluidized bed were measured. Video recordings were taken and image postprocessing allowed to identify the level of the fluidized bed, its height and its shape as viewed from the front. Based on the sieve analysis, accurate particle size distributions were calculated and implemented in the model. Afterward, simulations were performed and model parameters (especially those of the particle stress model and the gas-solid drag model) were adjusted to obtain satisfactory agreement with the experiments in terms of the time-averaged pressure drop, bed height, and qualitative behavior. ### Examination of Analytical Shear Stress Predictions over Simplified Dunes <a id="simplified-dunes"/> #### Speaker: Dr. Orie Cecil __Abstract:__ Existing process-based models for simulating dune evolution largely use analytical models for predictions of the wind-induced surface shear stress distribution. However, these analytical models face challenges when the topography exhibits steep slopes. In this presentation we utilize CFD to analyze the error trends of these analytical models for simplified topographies, and explore two data-driven approaches as possible alternatives for fast surface shear stress predictions. ### Multi-Layer Constructed Technosol Systems with Different Configurations for Green Roofs: Rhizobox Study Using Open-Source CNC Gardening Robot <a id="green-roofs"/> #### Speaker: Dr. Michal Sněhota __Abstract:__ This study evaluates the performance of multi-layered soil systems for green roof applications, which are common in blue green infrastructure. Unlike single-layered soils, these systems have different evapotranspiration, infiltration, contaminant removal, and plant support properties. However, the water and solute transport across the layer interfaces is poorly understood. We built 18 rhizoboxes with one, two, and four-layered soil systems on a raised bed on an open-air roof. We used intensive green roof substrate and coarsely grained expanded clay as the layer materials. We report the initial results of the first nine months of monitoring, during which we planted two plant species in the rhizoboxes after starting with bare-soil. We measured the water balance components to assess the hydraulic functioning of the soils. The next step is the application of noninvasive methods to investigate the pore geometry development and to study capillary barrier, finger flow, and air entrapment phenomena in the multi-layered soils. The aim is utilizing the experimental results to adapt a modeling approach for water and solute transport in natural soils to multi-layered constructed soils. Our study aims in long term to provide valuable insights for the design and management of green roofs with multi-layered soils. ### Physical modeling of near-surface geo-environments: Overview of the synthetic environment for near-surface sensing and experimentation (SENSE) Research Facility <a id="sense"/> #### Speaker: Dr. Andrew Trautz __Abstract:__ The SENSE is a new ERDC Research Facility built to support research pertaining to the atmosphere, near-surface environment, materials behavior, and sensor performance assessment. The facility is centered around a closed-circuit, climate-controlled, low-speed, meteorological wind tunnel that can be used to support traditional boundary layer investigations as well as coupled near-surface heat, mass, and momentum-based geo-environmental phenomenology. The latter is made possible through the unique design feature of the wind tunnel's test-section - a false floor that when removed allows soil test-beds ($1 \times 1 \times 7.5 \text{ m}$) packed with soils and vegetation of interest to be interfaced from below. This presentation provides an overview of the working theory behind, and capabilities of the SENSE Research Facility alongside past use cases and potential applications. <style> #doc { max-width: 970px; } h1:first-of-type { text-align: center; border: unset; margin-bottom: 0; } h1:first-of-type + h2 { text-align: center; margin: 0; margin-bottom: 1em; font-weight: normal; } th { text-align: left !important; } th:first-child, td:first-child { min-width: 9em; } th:nth-child(2), td:nth-child(2) { min-width: 13em; } img { border: 1px solid transparent; border-radius: 4px; } </style>