https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Sun, 07 Jun 2026 14:33:02 GMT 2026-06-07T14:33:02Z http://hdl.handle.net/10985/20621 Application of Non-toxic Yield Stress Fluids Porosimetry Method and Pore-Network Modelling to Characterize the Pore Size Distribution of Packs of Spherical Beads RODRIGUEZ DE CASTRO, Antonio; AGNAOU, Mehrez; AHMADI-SENICHAULT, Azita; OMARI, Abdelaziz With X-ray computed tomography still being flawed as a result of limitations in terms of spatial resolution and cost, toxic mercury intrusion porosimetry (MIP) is nowadays the prevailing technique to determine PSDs of most porous media. Recently, yield stress fluids porosimetry method (YSM) has been identified as a promising clean alternative to MIP. This technique is based on the particular percolation patterns followed by yield stress fluids, which only flow through certain pores when injected at a given pressure gradient. In previous works, YSM was used to characterize natural and synthetic porous media, and the results were compared with MIP showing reasonable agreement. However, considerable uncertainty still remains regarding the characterized pore dimension with each method arising from the highly complex geometry of the interstices in real porous media. Therefore, a critical stage for the validation of YSM consists in achieving successful characterization of model porous media with well-known pore morphology and topology. With this objective in mind, a set of four packs of glass beads each with a given monodisperse bead size were characterized in the present work using different porosimetry methods: experimental YSM, numerically simulation of MIP and pore-network extraction from a 3D image. The results provided by these techniques were compared, allowing the identification of the pore dimensions being characterized in each case. The results of this research elucidate the causes of the discrepancies between the considered porosimetry methods and demonstrate the usefulness of the PSD provided by YSM when predicting flow in porous media. Tue, 01 Jan 2019 00:00:00 GMT http://hdl.handle.net/10985/20621 2019-01-01T00:00:00Z RODRIGUEZ DE CASTRO, Antonio AGNAOU, Mehrez AHMADI-SENICHAULT, Azita OMARI, Abdelaziz With X-ray computed tomography still being flawed as a result of limitations in terms of spatial resolution and cost, toxic mercury intrusion porosimetry (MIP) is nowadays the prevailing technique to determine PSDs of most porous media. Recently, yield stress fluids porosimetry method (YSM) has been identified as a promising clean alternative to MIP. This technique is based on the particular percolation patterns followed by yield stress fluids, which only flow through certain pores when injected at a given pressure gradient. In previous works, YSM was used to characterize natural and synthetic porous media, and the results were compared with MIP showing reasonable agreement. However, considerable uncertainty still remains regarding the characterized pore dimension with each method arising from the highly complex geometry of the interstices in real porous media. Therefore, a critical stage for the validation of YSM consists in achieving successful characterization of model porous media with well-known pore morphology and topology. With this objective in mind, a set of four packs of glass beads each with a given monodisperse bead size were characterized in the present work using different porosimetry methods: experimental YSM, numerically simulation of MIP and pore-network extraction from a 3D image. The results provided by these techniques were compared, allowing the identification of the pore dimensions being characterized in each case. The results of this research elucidate the causes of the discrepancies between the considered porosimetry methods and demonstrate the usefulness of the PSD provided by YSM when predicting flow in porous media. http://hdl.handle.net/10985/20695 Empirical Flow Rate/Pressure Drop Relationships for Capillaries of Triangular and Rectangular Cross-Sections to be Used in Yield Stress Fluid Porosimetry MACKAYA, Terence Emery; AHMADI-SENICHAULT, Azita; OMARI, Abdelaziz; RODRIGUEZ DE CASTRO, Antonio The aim of the present work is to investigate the flow rate/pressure gradient relationship for the flow of yield stress fluids through rectilinear capillaries of non-circular cross-sections. These capillaries very often serve as basic elements in the modeling of porous media as bundles of capillaries or pore-network models. Based on the notions of shape coefficient and critical Bingham number, empirical flow rate/pressure gradient relationships have been proposed for both Bingham and Herschel–Bulkley fluids. The reliability of these relationships has been assessed by performing numerical simulations with the open-source Computational Fluid Dynamics (CFD) package OpenFOAM. For the considered cross-sectional shapes (equilateral triangle and square), and for a wide range of Bingham numbers, the predictions of the proposed empirical relationships have shown to be in very good agreement with the results of the current numerical simulations, as well as with previous results from the literature. An interesting feature of the proposed empirical relationships is the possibility to easily predict the total flow rate under a given imposed pressure gradient in a bundle of non-circular capillaries having any random distribution of inscribed circle radii. Furthermore, in the context of the yield stress fluid porosimetry method (YSM), experimental data may now be processed based upon bundles of capillaries with non-circular cross-sections. Fri, 01 Jan 2021 00:00:00 GMT http://hdl.handle.net/10985/20695 2021-01-01T00:00:00Z MACKAYA, Terence Emery AHMADI-SENICHAULT, Azita OMARI, Abdelaziz RODRIGUEZ DE CASTRO, Antonio The aim of the present work is to investigate the flow rate/pressure gradient relationship for the flow of yield stress fluids through rectilinear capillaries of non-circular cross-sections. These capillaries very often serve as basic elements in the modeling of porous media as bundles of capillaries or pore-network models. Based on the notions of shape coefficient and critical Bingham number, empirical flow rate/pressure gradient relationships have been proposed for both Bingham and Herschel–Bulkley fluids. The reliability of these relationships has been assessed by performing numerical simulations with the open-source Computational Fluid Dynamics (CFD) package OpenFOAM. For the considered cross-sectional shapes (equilateral triangle and square), and for a wide range of Bingham numbers, the predictions of the proposed empirical relationships have shown to be in very good agreement with the results of the current numerical simulations, as well as with previous results from the literature. An interesting feature of the proposed empirical relationships is the possibility to easily predict the total flow rate under a given imposed pressure gradient in a bundle of non-circular capillaries having any random distribution of inscribed circle radii. Furthermore, in the context of the yield stress fluid porosimetry method (YSM), experimental data may now be processed based upon bundles of capillaries with non-circular cross-sections. http://hdl.handle.net/10985/20629 Determination of the aperture distribution of rough-walled rock fractures with the non-toxic Yield Stress fluids porosimetry method RODRIGUEZ DE CASTRO, Antonio; AHMADI-SENICHAULT, Azita; OMARI, Abdelaziz Fractures in geological formations constitute high-conductivity conduits which potentially act as preferential paths during fluid injection in soil remediation and reservoir engineering operations. Recently, the measurement of the pressure drop under different flow rates during the flow of yield stress fluids in porous media has been proposed as the basis for an environmentally friendly method to characterize the Pore Size Distribution. However, the Yield Stress fluids porosimetry Method (YSM) has still not been extended to the characterization of the hydraulic aperture distribution of rough-walled rock fractures. The potential interest of such an extension is intense, considering that the distinct characteristics of rock fractures vs the matrix represent a burden to other traditional porosimetry techniques. In the particular case of X-ray microtomography, time-consuming calibration is often needed, and serious difficulties arise due to beam hardening and reconstruction artifacts. The specific objective of the present investigation is to adapt YSM to the characterization of rough-walled rock fractures. For this purpose, the results of laboratory experiments in which a yield stress fluid was injected through two natural rock fractures were exploited, and the YSM model and algorithm was adapted to the particular topological and geometrical features of flows in fractures. Moreover, numerical experiments were performed at the scale of a single 2D channel with variable aperture to identify the dimension characterized by YSM and decipher the yielding behaviour of the fluids. The present findings show that YSM can be successfully used to characterize the distribution of hydraulic apertures of the flow channels in rough-walled rock fractures. Furthermore, the numerical results revealed that the plug of stagnant fluid is located in the central part of these flow channels and breaks close to the constrictions, forming islands of unyielded fluid. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/20629 2020-01-01T00:00:00Z RODRIGUEZ DE CASTRO, Antonio AHMADI-SENICHAULT, Azita OMARI, Abdelaziz Fractures in geological formations constitute high-conductivity conduits which potentially act as preferential paths during fluid injection in soil remediation and reservoir engineering operations. Recently, the measurement of the pressure drop under different flow rates during the flow of yield stress fluids in porous media has been proposed as the basis for an environmentally friendly method to characterize the Pore Size Distribution. However, the Yield Stress fluids porosimetry Method (YSM) has still not been extended to the characterization of the hydraulic aperture distribution of rough-walled rock fractures. The potential interest of such an extension is intense, considering that the distinct characteristics of rock fractures vs the matrix represent a burden to other traditional porosimetry techniques. In the particular case of X-ray microtomography, time-consuming calibration is often needed, and serious difficulties arise due to beam hardening and reconstruction artifacts. The specific objective of the present investigation is to adapt YSM to the characterization of rough-walled rock fractures. For this purpose, the results of laboratory experiments in which a yield stress fluid was injected through two natural rock fractures were exploited, and the YSM model and algorithm was adapted to the particular topological and geometrical features of flows in fractures. Moreover, numerical experiments were performed at the scale of a single 2D channel with variable aperture to identify the dimension characterized by YSM and decipher the yielding behaviour of the fluids. The present findings show that YSM can be successfully used to characterize the distribution of hydraulic apertures of the flow channels in rough-walled rock fractures. Furthermore, the numerical results revealed that the plug of stagnant fluid is located in the central part of these flow channels and breaks close to the constrictions, forming islands of unyielded fluid. http://hdl.handle.net/10985/20622 Numerical investigation of Herschel–Bulkley fluid flows in 2D porous media: Yielding behaviour and tortuosity RODRIGUEZ DE CASTRO, Antonio; AGNAOU, Mehrez; AHMADI-SENICHAULT, Azita; OMARI, Abdelaziz Hydraulic tortuosity is commonly used as an input to macroscopic flow models in porous media, accounting for the sinuosity of the streamlines. It is well known that hydraulic tortuosity does not depend on the applied pressure gradient for Newtonian creeping flows. Nevertheless, this is not necessarily the case for yield stress fluids flows, given the directional nature of both yielding and shear-thinning behaviour. This study aims at a breakthrough on the relationship between the hydraulic tortuosity and the level of yielding. To do so, the hydraulic tortuosity of the flow paths is evaluated in 2D porous media by means of direct numerical simulations and subsequently put in relation with the morphological information of the medium provided by pore-network modelling. Moreover, the effects of pore dimensions, spatial disorder and rheological parameters on yielding behaviour are examined. In most situations, the reported tortuosity values are lower than those obtained for Newtonian fluids. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/20622 2020-01-01T00:00:00Z RODRIGUEZ DE CASTRO, Antonio AGNAOU, Mehrez AHMADI-SENICHAULT, Azita OMARI, Abdelaziz Hydraulic tortuosity is commonly used as an input to macroscopic flow models in porous media, accounting for the sinuosity of the streamlines. It is well known that hydraulic tortuosity does not depend on the applied pressure gradient for Newtonian creeping flows. Nevertheless, this is not necessarily the case for yield stress fluids flows, given the directional nature of both yielding and shear-thinning behaviour. This study aims at a breakthrough on the relationship between the hydraulic tortuosity and the level of yielding. To do so, the hydraulic tortuosity of the flow paths is evaluated in 2D porous media by means of direct numerical simulations and subsequently put in relation with the morphological information of the medium provided by pore-network modelling. Moreover, the effects of pore dimensions, spatial disorder and rheological parameters on yielding behaviour are examined. In most situations, the reported tortuosity values are lower than those obtained for Newtonian fluids. http://hdl.handle.net/10985/20627 Numerical porosimetry: Evaluation and comparison of yield stress fluids method, mercury intrusion porosimetry and pore network modelling approaches RODRIGUEZ DE CASTRO, Antonio; AGNAOU, Mehrez; AHMADI-SENICHAULT, Azita; OMARI, Abdelaziz Mercury Intrusion Porosimetry (MIP) is still today the reference porosimetry technique despite its environmental health and safety concerns. As a safe alternative, the Yield Stress fluids Method (YSM) consists in computing the Pore Size Distribution (PSD) of a given material from the pressure drop vs. flow rate measurements during injection of a yield stress fluid. However, the question arises whether the PSDs provided by YSM are representative of the actual pore dimensions. To answer this question, three numerical methods to obtain the PSD from digital images are proposed and compared in the present work. First, direct numerical simulations of YSM tests are performed in the considered media. Then, realistic PSDs are extracted from the images by using pore Network Modelling (NM). Furthermore, the obtained networks are also used to simulate MIP tests. The quantitative numerical results allow the evaluation of the relevance of YSM as an alternative to toxic MIP. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/20627 2020-01-01T00:00:00Z RODRIGUEZ DE CASTRO, Antonio AGNAOU, Mehrez AHMADI-SENICHAULT, Azita OMARI, Abdelaziz Mercury Intrusion Porosimetry (MIP) is still today the reference porosimetry technique despite its environmental health and safety concerns. As a safe alternative, the Yield Stress fluids Method (YSM) consists in computing the Pore Size Distribution (PSD) of a given material from the pressure drop vs. flow rate measurements during injection of a yield stress fluid. However, the question arises whether the PSDs provided by YSM are representative of the actual pore dimensions. To answer this question, three numerical methods to obtain the PSD from digital images are proposed and compared in the present work. First, direct numerical simulations of YSM tests are performed in the considered media. Then, realistic PSDs are extracted from the images by using pore Network Modelling (NM). Furthermore, the obtained networks are also used to simulate MIP tests. The quantitative numerical results allow the evaluation of the relevance of YSM as an alternative to toxic MIP. http://hdl.handle.net/10985/21599 Analysis of the length scale characterized by the yield stress fluids porosimetry method for consolidated media: comparison with pore network models and mercury intrusion porosimetry RODRIGUEZ DE CASTRO, Antonio; AHMADI-SENICHAULT, Azita; OMARI, Abdelaziz Substantial progress has been recently achieved in the development of a clean alternative tomercury intrusion porosimetry (MIP) based on single-phase flow measurements in porous samples using yield stress fluids. However, no study to date has examined the scale of the pore length actually provided by the yield stress fluids porosimetry method (YSM) in consolidated porous media. Indeed, while the results of YSM were compared to those provided by MIP in the past, the relationships between the characterized pore size distribution (PSD) and the actual pore geometry have still not been addressed for this type of porous media. This issue is of special interest to geoscientists involved in seeking relevant information from core characterization operations. With this aim in mind, the objective of the present paper is to evaluate the agreement between the PSDs characterized by YSM, the pore-opening size distributions provided byMIP tests, and the pore-throat and pore-body size distributions obtained from X-ray computed microtomography. For this purpose, a set of artificial and natural porous samples with permeability values extending over two magnitudes were characterized by using both YSM and MIP laboratory tests. Then, the results were matched to the model pore geometries extracted from digital images of the real microstructure. This analysis led to the main conclusion that YSM can be reliably used as an adequate substitute forMIP in the case of the investigated consolidated media, given the general agreement observed between these methods. Fri, 01 Jan 2021 00:00:00 GMT http://hdl.handle.net/10985/21599 2021-01-01T00:00:00Z RODRIGUEZ DE CASTRO, Antonio AHMADI-SENICHAULT, Azita OMARI, Abdelaziz Substantial progress has been recently achieved in the development of a clean alternative tomercury intrusion porosimetry (MIP) based on single-phase flow measurements in porous samples using yield stress fluids. However, no study to date has examined the scale of the pore length actually provided by the yield stress fluids porosimetry method (YSM) in consolidated porous media. Indeed, while the results of YSM were compared to those provided by MIP in the past, the relationships between the characterized pore size distribution (PSD) and the actual pore geometry have still not been addressed for this type of porous media. This issue is of special interest to geoscientists involved in seeking relevant information from core characterization operations. With this aim in mind, the objective of the present paper is to evaluate the agreement between the PSDs characterized by YSM, the pore-opening size distributions provided byMIP tests, and the pore-throat and pore-body size distributions obtained from X-ray computed microtomography. For this purpose, a set of artificial and natural porous samples with permeability values extending over two magnitudes were characterized by using both YSM and MIP laboratory tests. Then, the results were matched to the model pore geometries extracted from digital images of the real microstructure. This analysis led to the main conclusion that YSM can be reliably used as an adequate substitute forMIP in the case of the investigated consolidated media, given the general agreement observed between these methods. http://hdl.handle.net/10985/15656 Using Xanthan Gum Solutions to Characterize Porous Media with the Yield Stress Fluid Porosimetry Method: Robustness of the Method and Effects of Polymer Concentration RODRÍGUEZ DE CASTRO, Antonio; AHMADI, Azita; OMARI, Abdelaziz The yield stress fluids porosimetry method (YSM)was recently presented as a simple and non-toxic potential alternative to the extensively used mercury intrusion porosimetry (MIP). The success of YSM heavily relies on the choice of an appropriate yield stress fluid to be injected through the investigated porous medium. In previous works, xanthan gum aqueous solutions were used due to their ability to exhibit a pseudo-yield stress without substantial levels of unwanted thixotropy or viscoelasticity. Given that YSM is based on the existence of a yield stress, the accuracy of the obtained pore size distribution (PSD) crucially depends on the capacity of the injected fluid to emulate the shear rheology of a yield stress fluid. However, this capacity has still not been fully assessed in the case of xanthan gum solutions. Neither has the robustness of YSM with regard to errors in the determination of the shear-rheology parameters of the injected fluid been analysed. The shear viscosity of polymer solutions is known to be deeply influenced by polymer concentration. For these reasons, a first objective of this work is to evaluate the effect of polymer concentration on the accuracy of PSDs obtained by YSM when using xanthan gum solutions as injected fluids in laboratory experiments. To do so, xanthan gum solutions with different polymer concentrations were injected through analogous samples of a sintered silicate and the obtained PSDs were compared to the results of standard MIP. Moreover, the sensitivity of YSM to errors in the experimental determination of the shear-rheology parameters was also investigated through numerical experiments. The results of the present work permitted to gain further insight into the viability of YSM as an efficient alternative to MIP. Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/10985/15656 2018-01-01T00:00:00Z RODRÍGUEZ DE CASTRO, Antonio AHMADI, Azita OMARI, Abdelaziz The yield stress fluids porosimetry method (YSM)was recently presented as a simple and non-toxic potential alternative to the extensively used mercury intrusion porosimetry (MIP). The success of YSM heavily relies on the choice of an appropriate yield stress fluid to be injected through the investigated porous medium. In previous works, xanthan gum aqueous solutions were used due to their ability to exhibit a pseudo-yield stress without substantial levels of unwanted thixotropy or viscoelasticity. Given that YSM is based on the existence of a yield stress, the accuracy of the obtained pore size distribution (PSD) crucially depends on the capacity of the injected fluid to emulate the shear rheology of a yield stress fluid. However, this capacity has still not been fully assessed in the case of xanthan gum solutions. Neither has the robustness of YSM with regard to errors in the determination of the shear-rheology parameters of the injected fluid been analysed. The shear viscosity of polymer solutions is known to be deeply influenced by polymer concentration. For these reasons, a first objective of this work is to evaluate the effect of polymer concentration on the accuracy of PSDs obtained by YSM when using xanthan gum solutions as injected fluids in laboratory experiments. To do so, xanthan gum solutions with different polymer concentrations were injected through analogous samples of a sintered silicate and the obtained PSDs were compared to the results of standard MIP. Moreover, the sensitivity of YSM to errors in the experimental determination of the shear-rheology parameters was also investigated through numerical experiments. The results of the present work permitted to gain further insight into the viability of YSM as an efficient alternative to MIP.