George Biersack Selected to Serve on the Nominators Committee of the Emerson College

News release announces that Chairman of Communication Arts at the University of Dayton, George Biersack, has been selected to serve on the Nominators Committee of the Emerson College

Flow in Open Channel with Complex Solid Boundary

yesA two-dimensional steady potential flow theory is applied to calculate the flow in an open channel with complex solid boundaries. The boundary integral equations for the problem under investigation are first derived in an auxiliary plane by taking the Cauchy integral principal values. To overcome the difficulties of a nonlinear curvilinear solid boundary character and free water surface not being known a priori, the boundary integral equations are transformed to the physical plane by substituting the integral variables. As such, the proposed approach has the following advantages: (1) the angle of the curvilinear solid boundary as well as the location of free water surface (initially assumed) is a known function of coordinates in physical plane; and (2) the meshes can be flexibly assigned on the solid and free water surface boundaries along which the integration is performed. This avoids the difficulty of the traditional potential flow theory, which seeks a function to conformally map the geometry in physical plane onto an auxiliary plane. Furthermore, rough bed friction-induced energy loss is estimated using the Darcy-Weisbach equation and is solved together with the boundary integral equations using the proposed iterative method. The method has no stringent requirement for initial free-water surface position, while traditional potential flow methods usually have strict requirement for the initial free-surface profiles to ensure that the numerical computation is stable and convergent. Several typical open-channel flows have been calculated with high accuracy and limited computational time, indicating that the proposed method has general suitability for open-channel flows with complex geometry

Stochastic upscaling of hydrodynamic dispersion and retardation factor in a physically and chemically heterogeneous tropical soil

[EN] Stochastic upscaling of flow and reactive solute transport in a tropical soil is performed using real data collected in the laboratory. Upscaling of hydraulic conductivity, longitudinal hydrodynamic dispersion, and retardation factor were done using three different approaches of varying complexity. How uncertainty propagates after upscaling was also studied. The results show that upscaling must be taken into account if a good reproduction of the flow and transport behavior of a given soil is to be attained when modeled at larger than laboratory scales. The results also show that arrival time uncertainty was well reproduced after solute transport upscaling. This work represents a first demonstration of flow and reactive transport upscaling in a soil based on laboratory data. It also shows how simple upscaling methods can be incorporated into daily modeling practice using commercial flow and transport codes.The authors thank the financial support by the Brazilian National Council for Scientific and Technological Development (CNPq) (Project 401441/2014-8). The doctoral fellowship award to the first author by the Coordination of Improvement of Higher Level Personnel (CAPES) is acknowledged. The first author also thanks the international mobility grant awarded by CNPq, through the Sciences Without Borders program (Grant Number: 200597/2015-9). The international mobility grant awarded by Santander Mobility in cooperation with the University of Sao Paulo is also acknowledged. DHI-WASI is gratefully thanked for providing a FEFLOW license.Almeida De-Godoy, V.; Zuquette, L.; Gómez-Hernández, JJ. (2019). Stochastic upscaling of hydrodynamic dispersion and retardation factor in a physically and chemically heterogeneous tropical soil. 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Adjusting soil infiltration coefficients for groundwater level

Current UK guidance for the design of sustainable drainage systems recommends that infiltration devices, such as soakaways, permeable pavements and infiltration basins, should be able to operate during periods of extreme groundwater level. Furthermore, higher groundwater levels have recently been shown to cause a reduction in the empirical soil infiltration coefficient, as used in the design of infiltration devices. However, there is currently no simple method available to estimate the required reduction in the design infiltration coefficient to account for an extreme groundwater level. This paper uses exploratory numerical sub-surface saturated-unsaturated hydrological modelling to quantify the effect of groundwater level on the infiltration coefficient for six typical soil types. The fixed resolution finite element simulations are also benchmarked against a solution employing adaptive mesh refinement. The modelling results are distilled into charts and a simple equation to allow the calculation of adjustment factors, with which to reduce the design infiltration coefficient to account for a higher design groundwater level. Varying soil type sensitivity is highlighted. These factors could also be used to correct for soakage tests made during periods of lower groundwater level. Threshold depths to groundwater, below which no adjustment is required, are identified for each soil type

3D modelling of brine flow - a case study for a flooded salt mine

An abandoned and flooded historical salt mine located in Stassfurt (Germany) is studied within a joint research project. The objective of this project is to gain a better understanding of the dynamics of naturally or actively flooded salt mines. Within this survey the stability of the salt mine and the surrounding caprocks is studied. One task within this research framework is the computation of different density-dependent 3D groundwater transport models. Aim of these models is to improve the understanding of the impact of different remedial engineering solutions. For instance, it is studied which amount of salt will be dissolved due to pumping activities. Subsequently, the related potential of subsidence effects is assessed. A further challenge is the analysis of effects of the underground cavities on the groundwater and mass-transport dynamics. Detailed geometry of the mine workings is included in 3D model schematizations. Chemical reaction kinetics is also considered, where NaCl and MgCl2 are the dominant salt species. Precipitation and dissolution are controlled by the amount of available MgCl2. The consideration of these different salt types can be of importance as they possess different specific densities. Furthermore, permeability and porosity are also affected by precipitation and dissolution. It is shown that the impact of these different chemical and physical relations may have a relevant impact on the modeling result. The presented work is currently still in progress. However, the availability of 3D numerical models provides many advantages. Despite all limitations these models can serve as effective analysis tools to improve the understanding of the relevant processes

3D modeling of brine flow - a case study for a flooded salt mine

An abandoned and flooded historical salt mine located in Stassfurt (Germany) is studied within a joint research project. The objective of this project is to gain a better understanding of the dynamics of naturally or actively flooded salt mines. Within this survey the stability of the salt mine and the surrounding caprocks is studied. One task within this research framework is the computation of different density-dependent 3D groundwater transport models. Aim of these models is to improve the understanding of the impact of different remedial engineering solutions. For instance, it is studied which amount of salt will be dissolved due to pumping activities. Subsequently, the related potential of subsidence effects is assessed. A further challenge is the analysis of effects of the underground cavities on the groundwater and mass-transport dynamics. Detailed geometry of the mine workings is included in 3D model schematizations. Chemical reaction kinetics is also considered, where NaCl and MgCl2 are the dominant salt species. Precipitation and dissolution are controlled by the amount of available MgCl2. The consideration of these different salt types can be of importance as they possess different specific densities. Furthermore, permeability and porosity are also affected by precipitation and dissolution. It is shown that the impact of these different chemical and physical relations may have a relevant impact on the modeling result. The presented work is currently still in progress. However, the availability of 3D numerical models provides many advantages. Despite all limitations these models can serve as effective analysis tools to improve the understanding of the relevant processes