F. Inzoli | Politecnico di Milano (original) (raw)

Papers by F. Inzoli

Volume 1A, Symposia: Advances in Fluids Engineering Education; Turbomachinery Flow Predictions and Optimization; Applications in CFD; Bio-Inspired Fluid Mechanics; Droplet-Surface Interactions; CFD Verification and Validation; Development and Applications of Immersed Boundary Methods; DNS, LES, a..., 2014

A preliminary numerical study of the fluid dynamic behavior of flat and ribbed square duct is pre... more A preliminary numerical study of the fluid dynamic behavior of flat and ribbed square duct is presented. Fluid dynamics of two configurations is analyzed via Reynolds Averaged Navier Stokes (RANS) modeling in order to underline the main characteristics of each configuration and to give some information at global and local level. This kind of modeling is used as base for setting up a more detailed analysis such as Direct Numerical Simulation (DNS). Flat and ribbed square duct with a Reynolds number based on bulk velocity and hydraulic diameter of 10320 (Reτ=600 for the flat configuration) are analyzed and the results of the flat configuration are compared with available results obtained via DNS approach. The ribbed square duct is characterized by a two-pass configuration (aligned ribs in the top and bottom walls), with the duct height about six times the height of the obstacles for a blockage ratio of about 30%. Finally a pitch ratio (rib spacing to rib height) of 10 is used in order...

We present experimental investigations of two-phase (oil and water) relative permeability of labo... more We present experimental investigations of two-phase (oil and water) relative permeability of laboratory scale rock cores through a joint use of direct X-ray measurement and flow-through investigations. Experimental data embed key information relating relative permeability to observables. In this context, direct measurement of in-situ fluid saturation through X-Ray techniques has the unprecedented ability to characterize key processes occurring during the displacement of immiscible fluids through natural permeable materials. We illustrate the benefit of employing direct X-Ray measurements of fluid saturation through a set of laboratory experiments targeted to the estimate of two-phase relative permeabilities of homogeneous samples (sand pack and Berea sandston core). Data are obtained for a range of diverse fractional flow rates and provide information at saturations ranging from irreducible water content to residual oil saturation. Our X-Ray saturation data are consistent with an in...

Journal of Physics: Conference Series, 2017

The gas holdup is dimensionless parameter of fundamental and practical importance in the operatio... more The gas holdup is dimensionless parameter of fundamental and practical importance in the operation, design and scale-up of bubble columns. Unfortunately, the many relationships between the bubble column fluid dynamic parameters and the various variables characterizing the system make it difficult to find general correlations for the precise estimation of the gas holdup. Wilkinson et al. (1992), in their pioneering paper, proposed a correlation to predict the gas holdup in industrial-scale bubble columns, based on the physical properties of the phases and the operating conditions. However, this correlation lacks in generality, as it does not take in account the bubble column design. In this paper, we propose a generalization of the Wilkinson et al. (1992) gas holdup correlation to take into also the bubble column design parameters. Starting from considerations concerning the flow regime transition, corrective parameters are included to account for the effects introduced by the gas sparger openings, the bubble column aspect ratio and the bubble column diameter. The proposed correlation has been found to predict fairly well previously published gas holdup and flow regime transition data.

The International Journal of Artificial Organs, 1998

The clinical advantages achievable through pulsatile blood perfusion during cardio-pulmonary bypa... more The clinical advantages achievable through pulsatile blood perfusion during cardio-pulmonary bypass have recently suggested the design of new pulsatile systems for extracorporeal circulation. Still it is not clear whether current commercial membrane oxygenators could be adopted with such systems, since their behaviour with pulsatile perfusion has not been satisfactorily documented yet. In a previous paper, we assessed that pulsatile perfusion of a widely used hollow fibre oxygenator (Sorin® Monolyth) at 60 bpm provides more time-consistent oxygen transfer than steady perfusion. The present work is aimed to evaluate how the pulse frequency influences the gas transfer performance of the same device. The oxygenator was subjected to in vitro trials using a roller pump with pulsatile module (Stöckert Instrumente®) to generate pulsed flow. Four different pulse frequencies (45, 60, 75 and 90 bpm) were investigated at a fixed blood flow rate (4.0 l/min). The experiments lasting six hours we...

ABSTRACT Wet Flue Gas Desulphurisation (FGD) technology is the most frequently used scrubbing pro... more ABSTRACT Wet Flue Gas Desulphurisation (FGD) technology is the most frequently used scrubbing process for sulfur dioxide (SO 2) reduction from coal-fired utility boilers. A thermo-chemical computational fluid dynamic (CFD) model has been developed to describe the gas-and hydrodynamics of the scrubber, the liquid-wall interaction, the slurry evaporation and the sulphur dioxide absorption process in the slurry droplets. The continuous phase (gas) is modeled in the Eulerian framework while the discrete phase (liquid droplets) in the Lagrangian frame of reference. The injected spray can be altered through droplet-wall interaction, droplet evaporation, droplet-droplet collisions and nucleation. The first two mechanisms are the most important in terms of the total volume flux of the sprayed liquid being affected. Therefore they are the only two considered and they are treated in separately developed submodels.

Journal of Thermal Science, 2015

European Journal of Vascular Surgery, 1993

Hitherto the size of abdominal aortic aneurysms (AAA) has been considered the most important fact... more Hitherto the size of abdominal aortic aneurysms (AAA) has been considered the most important factor in determining the risk of rupture. For this reason most interest had been devoted to physical, echographic and tomographic analyses of the shape of AAA. However, it is known that rupture can also occur in small AAA. Other factors must be considered to have an important role in the natural history of aneurysms. The aim of this study was to characterise the mechanical stress in the wall of an AAA due to pressure in the presence of atherosclerosis, intraluminal thrombus and anatomical restraints. The Finite Elements Method (FEM) was used to determine wall stress distribution. Due to the simplicity of the AAA structure an axisymmetric model has been built. The results of the structural analysis confirms that maximum stress increases with diameter. These effects may be reduced by the presence of intraluminal thrombus, which in the models reduces maximum stress by up to 30%; however this is not the case for dissecting thrombus. On the other hand atherosclerotic plaques cause stress concentration and a significant increase in maximum wail stress. The risk of rupture can increase by about 200%. Finally the investigation shows the FEM is a versatile tool for studying the mechanics of vascular structures. It enables the influence of various parameters on wall stress to be quantified in diagnostic settings, and so could be useful for predicting the rupture of AAA, although at present such predictions are limited by data leakage and by the approximations used in the model.

Polymer Engineering & Science, 2007

ABSTRACT Polymer processing often activates material degradation, which affects to some extent th... more ABSTRACT Polymer processing often activates material degradation, which affects to some extent the performance or the life cycle of the obtained products. Polymer degradation is usually evidenced by molecular weight variations as consequence of exposure to high processing temperature and to relevant mechanical stresses. The degrading effects of melt extrusion under different thermo-mechanical conditions on polymethyl-methacrylate and polystyrene are investigated. Materials were processed at different temperatures and rates in a single screw extruder and in a capillary rheometer. Processed and as-received materials were analysed by Gel permeation chromatography, solution viscosity, and melt rheology. Evaluations of molecular weight and rheological behavior changes after processing, as compared with as-received materials, evidenced the extent of degradation in the different conditions. Experimental analysis was accompanied by finite elements simulation of the polymer flow and heat transmission within the extruder. This allowed an estimation of the expected shear stresses and temperatures distributions, thus indicating potentially critical situations. It was found that the materials processed at the highest rates in extruder presented lowest molecular weight reductions. This was attributed to the shorter residence time in the extruder and to the possibility of wall slip phenomena, which likely reduce the actual shear stress and viscous dissipation in the fast processing conditions. POLYM. ENG. SCI., 47:1813–1819, 2007. © 2007 Society of Plastics Engineers

Journal of Biomechanics, 1994

ASAIO Journal, 2002

A newly conceived blood pump for pulsatile cardiopulmonary bypass (CPB) is presented. The new dev... more A newly conceived blood pump for pulsatile cardiopulmonary bypass (CPB) is presented. The new device's main design features (fully disposable pumping head with ring shaped valves) were intended to overcome the factors that today limit the use of pulsatile blood pumps, i.e., the complexity and costs of devices. The pump was designed and analyzed by means of three-dimensional computational models, including solid computer assisted design of the pumping head and computational fluid-dynamic (CFD) analyses of the fluid domain and of its interaction with deformable components. A prototype of the device, integrated with the venous reservoir, was built to perform hydraulic in vitro tests with aims of both validating CFD results and verifying the new device's pumping behavior. Functional evaluation of the pump was carried out by using the device in a model circuit made with standard CPB components plus a mock hydraulic bench representing an adult patient's systemic circulation. A roller pump used in pulsatile mode (RP-PM) was used for comparison. At a 5 L/min flow rate, the pulsatile hydraulic power (<Wpuls>) delivered to the patient was approximately 15 mW for the RP-PM. The new pump proved to be able to deliver <Wpuls> up to 40 mW, thus providing a more physiological condition, closer to the <Wpuls> delivered by the natural heart (90-140 mW).

The simulation of parallel jets through steady state CFD has often proved to be problematic, in p... more The simulation of parallel jets through steady state CFD has often proved to be problematic, in particular when identical jets are simulated. In the present work the simulation of parallel jet mixing by the Unsteady Reynolds Averaged Navier-Stokes (URANS) methodology has been carried out. Such methodology has the potential to improve the results of steady state simulations, along with hybrid RANS-LES modeling and DES at a limited computational cost. The experimental setup of Kunz et al., consisting of five parallel pipe jets mixing in a rectangular confinement, has been chosen as a benchmark test because of its similarity with the geometry of the IRIS reactor. The ensemble averaged time-dependent Navier –Stokes equations have been solved through the finite volume code STAR-CD 4.06. The specific algorithm is the PISO algorithm specifically designed for transient calculations. Several numerical models have been prepared: the minimal symmetry unity (1/4 of the single jet) with boundary...

Experimental Thermal and Fluid Science, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Volume 1A, Symposia: Advances in Fluids Engineering Education; Turbomachinery Flow Predictions and Optimization; Applications in CFD; Bio-Inspired Fluid Mechanics; Droplet-Surface Interactions; CFD Verification and Validation; Development and Applications of Immersed Boundary Methods; DNS, LES, a..., 2014

A preliminary numerical study of the fluid dynamic behavior of flat and ribbed square duct is pre... more A preliminary numerical study of the fluid dynamic behavior of flat and ribbed square duct is presented. Fluid dynamics of two configurations is analyzed via Reynolds Averaged Navier Stokes (RANS) modeling in order to underline the main characteristics of each configuration and to give some information at global and local level. This kind of modeling is used as base for setting up a more detailed analysis such as Direct Numerical Simulation (DNS). Flat and ribbed square duct with a Reynolds number based on bulk velocity and hydraulic diameter of 10320 (Reτ=600 for the flat configuration) are analyzed and the results of the flat configuration are compared with available results obtained via DNS approach. The ribbed square duct is characterized by a two-pass configuration (aligned ribs in the top and bottom walls), with the duct height about six times the height of the obstacles for a blockage ratio of about 30%. Finally a pitch ratio (rib spacing to rib height) of 10 is used in order...

We present experimental investigations of two-phase (oil and water) relative permeability of labo... more We present experimental investigations of two-phase (oil and water) relative permeability of laboratory scale rock cores through a joint use of direct X-ray measurement and flow-through investigations. Experimental data embed key information relating relative permeability to observables. In this context, direct measurement of in-situ fluid saturation through X-Ray techniques has the unprecedented ability to characterize key processes occurring during the displacement of immiscible fluids through natural permeable materials. We illustrate the benefit of employing direct X-Ray measurements of fluid saturation through a set of laboratory experiments targeted to the estimate of two-phase relative permeabilities of homogeneous samples (sand pack and Berea sandston core). Data are obtained for a range of diverse fractional flow rates and provide information at saturations ranging from irreducible water content to residual oil saturation. Our X-Ray saturation data are consistent with an in...

Journal of Physics: Conference Series, 2017

The gas holdup is dimensionless parameter of fundamental and practical importance in the operatio... more The gas holdup is dimensionless parameter of fundamental and practical importance in the operation, design and scale-up of bubble columns. Unfortunately, the many relationships between the bubble column fluid dynamic parameters and the various variables characterizing the system make it difficult to find general correlations for the precise estimation of the gas holdup. Wilkinson et al. (1992), in their pioneering paper, proposed a correlation to predict the gas holdup in industrial-scale bubble columns, based on the physical properties of the phases and the operating conditions. However, this correlation lacks in generality, as it does not take in account the bubble column design. In this paper, we propose a generalization of the Wilkinson et al. (1992) gas holdup correlation to take into also the bubble column design parameters. Starting from considerations concerning the flow regime transition, corrective parameters are included to account for the effects introduced by the gas sparger openings, the bubble column aspect ratio and the bubble column diameter. The proposed correlation has been found to predict fairly well previously published gas holdup and flow regime transition data.

The International Journal of Artificial Organs, 1998

The clinical advantages achievable through pulsatile blood perfusion during cardio-pulmonary bypa... more The clinical advantages achievable through pulsatile blood perfusion during cardio-pulmonary bypass have recently suggested the design of new pulsatile systems for extracorporeal circulation. Still it is not clear whether current commercial membrane oxygenators could be adopted with such systems, since their behaviour with pulsatile perfusion has not been satisfactorily documented yet. In a previous paper, we assessed that pulsatile perfusion of a widely used hollow fibre oxygenator (Sorin® Monolyth) at 60 bpm provides more time-consistent oxygen transfer than steady perfusion. The present work is aimed to evaluate how the pulse frequency influences the gas transfer performance of the same device. The oxygenator was subjected to in vitro trials using a roller pump with pulsatile module (Stöckert Instrumente®) to generate pulsed flow. Four different pulse frequencies (45, 60, 75 and 90 bpm) were investigated at a fixed blood flow rate (4.0 l/min). The experiments lasting six hours we...

ABSTRACT Wet Flue Gas Desulphurisation (FGD) technology is the most frequently used scrubbing pro... more ABSTRACT Wet Flue Gas Desulphurisation (FGD) technology is the most frequently used scrubbing process for sulfur dioxide (SO 2) reduction from coal-fired utility boilers. A thermo-chemical computational fluid dynamic (CFD) model has been developed to describe the gas-and hydrodynamics of the scrubber, the liquid-wall interaction, the slurry evaporation and the sulphur dioxide absorption process in the slurry droplets. The continuous phase (gas) is modeled in the Eulerian framework while the discrete phase (liquid droplets) in the Lagrangian frame of reference. The injected spray can be altered through droplet-wall interaction, droplet evaporation, droplet-droplet collisions and nucleation. The first two mechanisms are the most important in terms of the total volume flux of the sprayed liquid being affected. Therefore they are the only two considered and they are treated in separately developed submodels.

Journal of Thermal Science, 2015

European Journal of Vascular Surgery, 1993

Hitherto the size of abdominal aortic aneurysms (AAA) has been considered the most important fact... more Hitherto the size of abdominal aortic aneurysms (AAA) has been considered the most important factor in determining the risk of rupture. For this reason most interest had been devoted to physical, echographic and tomographic analyses of the shape of AAA. However, it is known that rupture can also occur in small AAA. Other factors must be considered to have an important role in the natural history of aneurysms. The aim of this study was to characterise the mechanical stress in the wall of an AAA due to pressure in the presence of atherosclerosis, intraluminal thrombus and anatomical restraints. The Finite Elements Method (FEM) was used to determine wall stress distribution. Due to the simplicity of the AAA structure an axisymmetric model has been built. The results of the structural analysis confirms that maximum stress increases with diameter. These effects may be reduced by the presence of intraluminal thrombus, which in the models reduces maximum stress by up to 30%; however this is not the case for dissecting thrombus. On the other hand atherosclerotic plaques cause stress concentration and a significant increase in maximum wail stress. The risk of rupture can increase by about 200%. Finally the investigation shows the FEM is a versatile tool for studying the mechanics of vascular structures. It enables the influence of various parameters on wall stress to be quantified in diagnostic settings, and so could be useful for predicting the rupture of AAA, although at present such predictions are limited by data leakage and by the approximations used in the model.

Polymer Engineering & Science, 2007

ABSTRACT Polymer processing often activates material degradation, which affects to some extent th... more ABSTRACT Polymer processing often activates material degradation, which affects to some extent the performance or the life cycle of the obtained products. Polymer degradation is usually evidenced by molecular weight variations as consequence of exposure to high processing temperature and to relevant mechanical stresses. The degrading effects of melt extrusion under different thermo-mechanical conditions on polymethyl-methacrylate and polystyrene are investigated. Materials were processed at different temperatures and rates in a single screw extruder and in a capillary rheometer. Processed and as-received materials were analysed by Gel permeation chromatography, solution viscosity, and melt rheology. Evaluations of molecular weight and rheological behavior changes after processing, as compared with as-received materials, evidenced the extent of degradation in the different conditions. Experimental analysis was accompanied by finite elements simulation of the polymer flow and heat transmission within the extruder. This allowed an estimation of the expected shear stresses and temperatures distributions, thus indicating potentially critical situations. It was found that the materials processed at the highest rates in extruder presented lowest molecular weight reductions. This was attributed to the shorter residence time in the extruder and to the possibility of wall slip phenomena, which likely reduce the actual shear stress and viscous dissipation in the fast processing conditions. POLYM. ENG. SCI., 47:1813–1819, 2007. © 2007 Society of Plastics Engineers

Journal of Biomechanics, 1994

ASAIO Journal, 2002

A newly conceived blood pump for pulsatile cardiopulmonary bypass (CPB) is presented. The new dev... more A newly conceived blood pump for pulsatile cardiopulmonary bypass (CPB) is presented. The new device's main design features (fully disposable pumping head with ring shaped valves) were intended to overcome the factors that today limit the use of pulsatile blood pumps, i.e., the complexity and costs of devices. The pump was designed and analyzed by means of three-dimensional computational models, including solid computer assisted design of the pumping head and computational fluid-dynamic (CFD) analyses of the fluid domain and of its interaction with deformable components. A prototype of the device, integrated with the venous reservoir, was built to perform hydraulic in vitro tests with aims of both validating CFD results and verifying the new device's pumping behavior. Functional evaluation of the pump was carried out by using the device in a model circuit made with standard CPB components plus a mock hydraulic bench representing an adult patient's systemic circulation. A roller pump used in pulsatile mode (RP-PM) was used for comparison. At a 5 L/min flow rate, the pulsatile hydraulic power (<Wpuls>) delivered to the patient was approximately 15 mW for the RP-PM. The new pump proved to be able to deliver <Wpuls> up to 40 mW, thus providing a more physiological condition, closer to the <Wpuls> delivered by the natural heart (90-140 mW).

The simulation of parallel jets through steady state CFD has often proved to be problematic, in p... more The simulation of parallel jets through steady state CFD has often proved to be problematic, in particular when identical jets are simulated. In the present work the simulation of parallel jet mixing by the Unsteady Reynolds Averaged Navier-Stokes (URANS) methodology has been carried out. Such methodology has the potential to improve the results of steady state simulations, along with hybrid RANS-LES modeling and DES at a limited computational cost. The experimental setup of Kunz et al., consisting of five parallel pipe jets mixing in a rectangular confinement, has been chosen as a benchmark test because of its similarity with the geometry of the IRIS reactor. The ensemble averaged time-dependent Navier –Stokes equations have been solved through the finite volume code STAR-CD 4.06. The specific algorithm is the PISO algorithm specifically designed for transient calculations. Several numerical models have been prepared: the minimal symmetry unity (1/4 of the single jet) with boundary...

Experimental Thermal and Fluid Science, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.