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Papers by Ravid Rosenzweig

Research paper thumbnail of Anaerobic biodegradation of MTBE in a field site above the Israeli Coastal Aquifer: evidence from δ 13 C compound-specific isotope analysis

Journal of Chemical Technology & Biotechnology, 2016

Research paper thumbnail of Theoretical and numerical study of flow at the interface of porous media

Geophysical Monograph Series, 2000

ABSTRACT A solution to the problem of laminar flow above a porous surface is essential when inves... more ABSTRACT A solution to the problem of laminar flow above a porous surface is essential when investigating phenomena such as erosion, re-suspension, or mass transfer between the porous media and the flow above it. Previous studies have provided theoretical, experimental, and numerical insight, but failed to provide a general, useful tool for predicting the macroscopic flow in domains that involve an interface between porous regions and free flow regions. Many studies have used the Brinkman equation, while others have shown that it does not represent the actual flow conditions at the interface. In this paper, we show that the interface macroscopic velocity can be modeled by introducing a modification to the Brinkman equation. A moving average approach was proved to be successful when choosing the correct representative elementary volume and comparing the macroscopic solution with the average microscopic flow. As the size of the representative elementary volume was found to be equal to the product of the square root of the permeability and an exponential function of the porosity, a closed solution is now available. The macroscopic model was developed while considering a 2D porous media made of multiple parallel grooves. The model was then applied using a 3D porous media, which has, in the horizontal plane, a shape of the fractal set "Sierpinski Carpet." Given the properties of the porous media (porosity and permeability), the flow height, the fluid viscosity, and its driving force, a complete macroscopic solution of the interface flow is obtained.

Research paper thumbnail of Solid matrix partition by fracture networks

Physical review. E, Statistical, nonlinear, and soft matter physics, 2014

The geometrical properties of the matrix blocks formed by a random fracture network are investiga... more The geometrical properties of the matrix blocks formed by a random fracture network are investigated numerically, for a wide range of fracture shapes and for fracture densities ranging from the dilute limit to well above the threshold where the material is entirely partitioned into finite blocks. The main block characteristics are the density and volume fraction, the mean volume and surface area, and their number of faces. In the dilute limit, general expressions for these characteristics are obtained, which provide a good approximation of the numerical data for any fracture shape. In the dense regime, most properties are governed by power laws, which involve two fitted exponents independent of the fracture shape. The shape factors identified in the dilute limit remain relevant for dense networks and can be used to formulate a general model for the block characteristics, valid up to the total matrix fracturation. The transition density when this occurs is determined. It can also be ...

Research paper thumbnail of Modeling biofilm dynamics and hydraulic properties in variably saturated soils using a channel network model

Water Resources Research, 2014

ABSTRACT Biofilm effects on water flow in unsaturated environments have largely been ignored in t... more ABSTRACT Biofilm effects on water flow in unsaturated environments have largely been ignored in the past. However, intensive engineered systems that involve elevated organic loads such as wastewater irrigation, effluent recharge and bioremediation processes make understanding how biofilms affect flow highly important. In the current work we present a channel-network model that incorporates water flow, substrate transport and biofilm dynamics to simulate the alteration of soil hydraulic properties, namely water retention and conductivity. The change in hydraulic properties due to biofilm growth is not trivial and depends highly on the spatial distribution of the biofilm development. Our results indicate that the substrate mass transfer coefficient across the water-biofilm interface dominates the spatio-temporal distribution of biofilm. High mass transfer coefficients lead to uncontrolled biofilm growth close to the substrate source, resulting in preferential clogging of the soil. Low mass transfer coefficients, on the other hand, lead to a more uniform biofilm distribution. The first scenario leads to a dramatic reduction of the hydraulic conductivity with almost no change in water retention, whereas the second scenario has a smaller effect on conductivity but a larger influence on retention. The current modeling approach identifies key factors that still need to be studied and opens the way for simulation and optimization of processes involving significant biological activity in unsaturated soils.

Research paper thumbnail of Modified Brinkman equation for a free flow problem at the interface of porous surfaces: The Cantor-Taylor brush configuration case

Water Resources Research, 2002

... U. Shavit, G. Bar-Yosef, and R. Rosenzweig Agricultural Engineering, Technion, Haifa, Israel ... more ... U. Shavit, G. Bar-Yosef, and R. Rosenzweig Agricultural Engineering, Technion, Haifa, Israel ... to bounded flow problems [Beavers and Joseph, 1967; Taylor, 1971; Neale and Nader, 1974; Vignes-Adler et al., 1987; Martys et al., 1994; James and Davis, 2001; Alazmi and Vafai ...

Research paper thumbnail of The laminar flow field at the interface of a Sierpinski carpet configuration

Water Resources Research, 2007

1] The problem of laminar flow in a combined free and saturated porous domain was investigated us... more 1] The problem of laminar flow in a combined free and saturated porous domain was investigated using a Sierpinski carpet configuration. The three-dimensional steady state microscale velocities were measured using a particle image velocimeter and computed numerically. The macroscale velocity profiles were then obtained by averaging the microscale velocities. A comparison between the measured and computed velocities showed a good fit. The macroscale velocity profile was calculated using the modified Brinkman equation (MBE), which was recently derived for two-dimensional brush configurations. The MBE was developed for unidirectional, laminar flows, assuming that the porous medium planar porosity follows a step function. A new analytical solution of the MBE was developed and applied using no calibration or curve fitting. It was shown that although the MBE was originally derived for a unidirectional microscopic flow field, the macroscopic representation of the complex microscopic flow in the Sierpinski configuration can be well described by the solutions of the MBE.

Research paper thumbnail of A Channel Network Model as a Framework for Characterizing Variably Saturated Flow in Biofilm-Affected Soils

Vadose Zone Journal, 2013

Research paper thumbnail of The Influence of Biofilm Spatial Distribution Scenarios on Hydraulic Conductivity of Unsaturated Soils

Vadose Zone Journal, 2009

... and D. Crawford. 1991. Influence of biofilm accumulation on porous media hydrodynamics. Envir... more ... and D. Crawford. 1991. Influence of biofilm accumulation on porous media hydrodynamics. Environ. Sci. Technol. 25:1305–1311. ↵ Mostafa, M., and PJ Van Geel. 2007. ... Water Resour. Res. 12:513–522. CrossRef. ↵ Nunan, N., KJ Wu, IM Young, JW Crawford, and K. Ritz. 2003. ...

Research paper thumbnail of Free Flow at the Interface of Porous Surfaces: A Generalization of the Taylor Brush Configuration

Transport in Porous Media, 2000

A solution to the problem of shallow laminar water flow above a porous surface is essential when ... more A solution to the problem of shallow laminar water flow above a porous surface is essential when modeling phenomena such as erosion, resuspension, and mass transfer between the porous media and the flow above it. Previous studies proposed theoretical, experimental, and numerical insight with no single general solution to the problem. Many studies have used the Brinkman equation, while others showed that it does not represent the actual interface flow conditions. In this paper we show that the interface macroscopic velocity can be accurately modeled by introducing a modification to the Brinkman equation. A moving average approach was proved to be successful when choosing the correct representative elementary volume and comparing the macroscopic solution with the average microscopic flow. As the size of the representative elementary volume was found to be equal to the product of the square root of the permeability and an exponential function of the porosity, a general solution is now available for any brush configuration. Given the properties of the porous media (porosity and permeability), the flow height and its driving force, a complete macroscopic solution of the interface flow is obtained.

Research paper thumbnail of Water Retention Curves of Biofilm-Affected Soils using Xanthan as an Analogue

Soil Science Society of America Journal, 2012

Research paper thumbnail of Deposition of fractal-like soot aggregates in the human respiratory tract

Journal of Aerosol Science, 2011

Deposition of diesel exhaust particles in the human respiratory tract is calculated in terms of t... more Deposition of diesel exhaust particles in the human respiratory tract is calculated in terms of the equivalent mobility diameter while accounting for the aggregate's number of primary spherules, Np, and its mass mobility fractal dimension. The size and shape of the soot particles studied correspond to emissions from diesel engines under different loading conditions. The aggregate's morphology, characterized by the

Research paper thumbnail of Anaerobic biodegradation of MTBE in a field site above the Israeli Coastal Aquifer: evidence from δ 13 C compound-specific isotope analysis

Journal of Chemical Technology & Biotechnology, 2016

Research paper thumbnail of Theoretical and numerical study of flow at the interface of porous media

Geophysical Monograph Series, 2000

ABSTRACT A solution to the problem of laminar flow above a porous surface is essential when inves... more ABSTRACT A solution to the problem of laminar flow above a porous surface is essential when investigating phenomena such as erosion, re-suspension, or mass transfer between the porous media and the flow above it. Previous studies have provided theoretical, experimental, and numerical insight, but failed to provide a general, useful tool for predicting the macroscopic flow in domains that involve an interface between porous regions and free flow regions. Many studies have used the Brinkman equation, while others have shown that it does not represent the actual flow conditions at the interface. In this paper, we show that the interface macroscopic velocity can be modeled by introducing a modification to the Brinkman equation. A moving average approach was proved to be successful when choosing the correct representative elementary volume and comparing the macroscopic solution with the average microscopic flow. As the size of the representative elementary volume was found to be equal to the product of the square root of the permeability and an exponential function of the porosity, a closed solution is now available. The macroscopic model was developed while considering a 2D porous media made of multiple parallel grooves. The model was then applied using a 3D porous media, which has, in the horizontal plane, a shape of the fractal set "Sierpinski Carpet." Given the properties of the porous media (porosity and permeability), the flow height, the fluid viscosity, and its driving force, a complete macroscopic solution of the interface flow is obtained.

Research paper thumbnail of Solid matrix partition by fracture networks

Physical review. E, Statistical, nonlinear, and soft matter physics, 2014

The geometrical properties of the matrix blocks formed by a random fracture network are investiga... more The geometrical properties of the matrix blocks formed by a random fracture network are investigated numerically, for a wide range of fracture shapes and for fracture densities ranging from the dilute limit to well above the threshold where the material is entirely partitioned into finite blocks. The main block characteristics are the density and volume fraction, the mean volume and surface area, and their number of faces. In the dilute limit, general expressions for these characteristics are obtained, which provide a good approximation of the numerical data for any fracture shape. In the dense regime, most properties are governed by power laws, which involve two fitted exponents independent of the fracture shape. The shape factors identified in the dilute limit remain relevant for dense networks and can be used to formulate a general model for the block characteristics, valid up to the total matrix fracturation. The transition density when this occurs is determined. It can also be ...

Research paper thumbnail of Modeling biofilm dynamics and hydraulic properties in variably saturated soils using a channel network model

Water Resources Research, 2014

ABSTRACT Biofilm effects on water flow in unsaturated environments have largely been ignored in t... more ABSTRACT Biofilm effects on water flow in unsaturated environments have largely been ignored in the past. However, intensive engineered systems that involve elevated organic loads such as wastewater irrigation, effluent recharge and bioremediation processes make understanding how biofilms affect flow highly important. In the current work we present a channel-network model that incorporates water flow, substrate transport and biofilm dynamics to simulate the alteration of soil hydraulic properties, namely water retention and conductivity. The change in hydraulic properties due to biofilm growth is not trivial and depends highly on the spatial distribution of the biofilm development. Our results indicate that the substrate mass transfer coefficient across the water-biofilm interface dominates the spatio-temporal distribution of biofilm. High mass transfer coefficients lead to uncontrolled biofilm growth close to the substrate source, resulting in preferential clogging of the soil. Low mass transfer coefficients, on the other hand, lead to a more uniform biofilm distribution. The first scenario leads to a dramatic reduction of the hydraulic conductivity with almost no change in water retention, whereas the second scenario has a smaller effect on conductivity but a larger influence on retention. The current modeling approach identifies key factors that still need to be studied and opens the way for simulation and optimization of processes involving significant biological activity in unsaturated soils.

Research paper thumbnail of Modified Brinkman equation for a free flow problem at the interface of porous surfaces: The Cantor-Taylor brush configuration case

Water Resources Research, 2002

... U. Shavit, G. Bar-Yosef, and R. Rosenzweig Agricultural Engineering, Technion, Haifa, Israel ... more ... U. Shavit, G. Bar-Yosef, and R. Rosenzweig Agricultural Engineering, Technion, Haifa, Israel ... to bounded flow problems [Beavers and Joseph, 1967; Taylor, 1971; Neale and Nader, 1974; Vignes-Adler et al., 1987; Martys et al., 1994; James and Davis, 2001; Alazmi and Vafai ...

Research paper thumbnail of The laminar flow field at the interface of a Sierpinski carpet configuration

Water Resources Research, 2007

1] The problem of laminar flow in a combined free and saturated porous domain was investigated us... more 1] The problem of laminar flow in a combined free and saturated porous domain was investigated using a Sierpinski carpet configuration. The three-dimensional steady state microscale velocities were measured using a particle image velocimeter and computed numerically. The macroscale velocity profiles were then obtained by averaging the microscale velocities. A comparison between the measured and computed velocities showed a good fit. The macroscale velocity profile was calculated using the modified Brinkman equation (MBE), which was recently derived for two-dimensional brush configurations. The MBE was developed for unidirectional, laminar flows, assuming that the porous medium planar porosity follows a step function. A new analytical solution of the MBE was developed and applied using no calibration or curve fitting. It was shown that although the MBE was originally derived for a unidirectional microscopic flow field, the macroscopic representation of the complex microscopic flow in the Sierpinski configuration can be well described by the solutions of the MBE.

Research paper thumbnail of A Channel Network Model as a Framework for Characterizing Variably Saturated Flow in Biofilm-Affected Soils

Vadose Zone Journal, 2013

Research paper thumbnail of The Influence of Biofilm Spatial Distribution Scenarios on Hydraulic Conductivity of Unsaturated Soils

Vadose Zone Journal, 2009

... and D. Crawford. 1991. Influence of biofilm accumulation on porous media hydrodynamics. Envir... more ... and D. Crawford. 1991. Influence of biofilm accumulation on porous media hydrodynamics. Environ. Sci. Technol. 25:1305–1311. ↵ Mostafa, M., and PJ Van Geel. 2007. ... Water Resour. Res. 12:513–522. CrossRef. ↵ Nunan, N., KJ Wu, IM Young, JW Crawford, and K. Ritz. 2003. ...

Research paper thumbnail of Free Flow at the Interface of Porous Surfaces: A Generalization of the Taylor Brush Configuration

Transport in Porous Media, 2000

A solution to the problem of shallow laminar water flow above a porous surface is essential when ... more A solution to the problem of shallow laminar water flow above a porous surface is essential when modeling phenomena such as erosion, resuspension, and mass transfer between the porous media and the flow above it. Previous studies proposed theoretical, experimental, and numerical insight with no single general solution to the problem. Many studies have used the Brinkman equation, while others showed that it does not represent the actual interface flow conditions. In this paper we show that the interface macroscopic velocity can be accurately modeled by introducing a modification to the Brinkman equation. A moving average approach was proved to be successful when choosing the correct representative elementary volume and comparing the macroscopic solution with the average microscopic flow. As the size of the representative elementary volume was found to be equal to the product of the square root of the permeability and an exponential function of the porosity, a general solution is now available for any brush configuration. Given the properties of the porous media (porosity and permeability), the flow height and its driving force, a complete macroscopic solution of the interface flow is obtained.

Research paper thumbnail of Water Retention Curves of Biofilm-Affected Soils using Xanthan as an Analogue

Soil Science Society of America Journal, 2012

Research paper thumbnail of Deposition of fractal-like soot aggregates in the human respiratory tract

Journal of Aerosol Science, 2011

Deposition of diesel exhaust particles in the human respiratory tract is calculated in terms of t... more Deposition of diesel exhaust particles in the human respiratory tract is calculated in terms of the equivalent mobility diameter while accounting for the aggregate's number of primary spherules, Np, and its mass mobility fractal dimension. The size and shape of the soot particles studied correspond to emissions from diesel engines under different loading conditions. The aggregate's morphology, characterized by the