Rheo-PIV Analysis of the Yielding and Flow of Model Waxy Crude Oils

Waxes are a commonly encountered precipitate that can result in the gelation of crude oils and cessation of flow in pipelines. In this work, we develop a model wax–oil system that exhibits rheological behavior similar to that of waxy crude oils encountered in production scenarios. To study the consequences of gelation on the rheology of the model system, we perform simultaneous measurements of the bulk flow behavior using rheometry and of the local shearing deformation using particle image velocimetry. The bulk rheological measurements are correlated to deviations from the linear velocity profile anticipated for a homogeneous sample undergoing simple shearthis provides new insights into the structural and rheological evolution of these wax–oil systems under representative shearing conditions. The restart of flow and breakdown of the gelled wax–oil structure is observed under two scenariosa constant applied stress and a constant applied strain rate. In addition, the effect of varying surface roughness on flow restart is investigated by comparing the temporal evolution of the velocity fields for an initially gelled fluid in contact with both a roughened and smooth surface. The material response in each case indicates that some classes of surface act as slip inhibitors and prevent the gelled wax–oil system from slipping against them. This promotes bulk deformation and the more rapid breakdown of the gel structure. These results are consistent with recent observations in other jammed/yielding systems and have an immediate bearing on pipeline restart strategies

Arrested Chain Growth During Magnetic Directed Particle Assembly in Yield Stress Matrix Fluids

The process of assembling particles into organized functional structures is influenced by the rheological properties of the matrix fluid in which the assembly takes place. Therefore, tuning these properties represents a viable and as yet unexplored approach for controlling particle assembly. In this Letter, we examine the effect of the matrix fluid yield stress on the directed assembly of polarizable particles into linear chains under a uniform external magnetic field. Using particle-level simulations with a simple yield stress model, we find that chain growth follows the same trajectory as in Newtonian matrix fluids up to a critical time that depends on the balance between the yield stress and the strength of magnetic interactions between particles; subsequently, the system undergoes structural arrest. Appropriate dimensionless groups for characterizing the arresting behavior are determined and relationships between these groups and the resulting structural properties are presented. Since field-induced structures can be indefinitely stabilized by the matrix fluid yield stress and “frozen” into place as desired, this approach may facilitate the assembly of more complex and sophisticated structures

Arrested Chain Growth During Magnetic Directed Particle Assembly in Yield Stress Matrix Fluids

The process of assembling particles into organized functional structures is influenced by the rheological properties of the matrix fluid in which the assembly takes place. Therefore, tuning these properties represents a viable and as yet unexplored approach for controlling particle assembly. In this Letter, we examine the effect of the matrix fluid yield stress on the directed assembly of polarizable particles into linear chains under a uniform external magnetic field. Using particle-level simulations with a simple yield stress model, we find that chain growth follows the same trajectory as in Newtonian matrix fluids up to a critical time that depends on the balance between the yield stress and the strength of magnetic interactions between particles; subsequently, the system undergoes structural arrest. Appropriate dimensionless groups for characterizing the arresting behavior are determined and relationships between these groups and the resulting structural properties are presented. Since field-induced structures can be indefinitely stabilized by the matrix fluid yield stress and “frozen” into place as desired, this approach may facilitate the assembly of more complex and sophisticated structures

Arrested Chain Growth During Magnetic Directed Particle Assembly in Yield Stress Matrix Fluids

The process of assembling particles into organized functional structures is influenced by the rheological properties of the matrix fluid in which the assembly takes place. Therefore, tuning these properties represents a viable and as yet unexplored approach for controlling particle assembly. In this Letter, we examine the effect of the matrix fluid yield stress on the directed assembly of polarizable particles into linear chains under a uniform external magnetic field. Using particle-level simulations with a simple yield stress model, we find that chain growth follows the same trajectory as in Newtonian matrix fluids up to a critical time that depends on the balance between the yield stress and the strength of magnetic interactions between particles; subsequently, the system undergoes structural arrest. Appropriate dimensionless groups for characterizing the arresting behavior are determined and relationships between these groups and the resulting structural properties are presented. Since field-induced structures can be indefinitely stabilized by the matrix fluid yield stress and “frozen” into place as desired, this approach may facilitate the assembly of more complex and sophisticated structures

Arrested Chain Growth During Magnetic Directed Particle Assembly in Yield Stress Matrix Fluids

The process of assembling particles into organized functional structures is influenced by the rheological properties of the matrix fluid in which the assembly takes place. Therefore, tuning these properties represents a viable and as yet unexplored approach for controlling particle assembly. In this Letter, we examine the effect of the matrix fluid yield stress on the directed assembly of polarizable particles into linear chains under a uniform external magnetic field. Using particle-level simulations with a simple yield stress model, we find that chain growth follows the same trajectory as in Newtonian matrix fluids up to a critical time that depends on the balance between the yield stress and the strength of magnetic interactions between particles; subsequently, the system undergoes structural arrest. Appropriate dimensionless groups for characterizing the arresting behavior are determined and relationships between these groups and the resulting structural properties are presented. Since field-induced structures can be indefinitely stabilized by the matrix fluid yield stress and “frozen” into place as desired, this approach may facilitate the assembly of more complex and sophisticated structures

Arrested Chain Growth During Magnetic Directed Particle Assembly in Yield Stress Matrix Fluids

The process of assembling particles into organized functional structures is influenced by the rheological properties of the matrix fluid in which the assembly takes place. Therefore, tuning these properties represents a viable and as yet unexplored approach for controlling particle assembly. In this Letter, we examine the effect of the matrix fluid yield stress on the directed assembly of polarizable particles into linear chains under a uniform external magnetic field. Using particle-level simulations with a simple yield stress model, we find that chain growth follows the same trajectory as in Newtonian matrix fluids up to a critical time that depends on the balance between the yield stress and the strength of magnetic interactions between particles; subsequently, the system undergoes structural arrest. Appropriate dimensionless groups for characterizing the arresting behavior are determined and relationships between these groups and the resulting structural properties are presented. Since field-induced structures can be indefinitely stabilized by the matrix fluid yield stress and “frozen” into place as desired, this approach may facilitate the assembly of more complex and sophisticated structures

Arrested Chain Growth During Magnetic Directed Particle Assembly in Yield Stress Matrix Fluids

The process of assembling particles into organized functional structures is influenced by the rheological properties of the matrix fluid in which the assembly takes place. Therefore, tuning these properties represents a viable and as yet unexplored approach for controlling particle assembly. In this Letter, we examine the effect of the matrix fluid yield stress on the directed assembly of polarizable particles into linear chains under a uniform external magnetic field. Using particle-level simulations with a simple yield stress model, we find that chain growth follows the same trajectory as in Newtonian matrix fluids up to a critical time that depends on the balance between the yield stress and the strength of magnetic interactions between particles; subsequently, the system undergoes structural arrest. Appropriate dimensionless groups for characterizing the arresting behavior are determined and relationships between these groups and the resulting structural properties are presented. Since field-induced structures can be indefinitely stabilized by the matrix fluid yield stress and “frozen” into place as desired, this approach may facilitate the assembly of more complex and sophisticated structures

Arrested Chain Growth During Magnetic Directed Particle Assembly in Yield Stress Matrix Fluids

The process of assembling particles into organized functional structures is influenced by the rheological properties of the matrix fluid in which the assembly takes place. Therefore, tuning these properties represents a viable and as yet unexplored approach for controlling particle assembly. In this Letter, we examine the effect of the matrix fluid yield stress on the directed assembly of polarizable particles into linear chains under a uniform external magnetic field. Using particle-level simulations with a simple yield stress model, we find that chain growth follows the same trajectory as in Newtonian matrix fluids up to a critical time that depends on the balance between the yield stress and the strength of magnetic interactions between particles; subsequently, the system undergoes structural arrest. Appropriate dimensionless groups for characterizing the arresting behavior are determined and relationships between these groups and the resulting structural properties are presented. Since field-induced structures can be indefinitely stabilized by the matrix fluid yield stress and “frozen” into place as desired, this approach may facilitate the assembly of more complex and sophisticated structures

Painting the town green The use of urban sustainability indicators in the United States of America

Includes bibliographical references. Title from coverAvailable from British Library Document Supply Centre- DSC:m03/20472 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Rheology as a Mechanoscopic Method to Monitor Mineralization in Hydrogels

Biominerals have been widely studied due to their unique mechanical properties, afforded by their inorganic–organic composite structure and well-controlled growth in macromolecular environments. However, a lack of suitable characterization techniques for inorganic minerals in organic-rich media has prevented a full understanding of biomineralization. Here, we applied rheometry to study mineral nucleation and growth dynamics by measuring viscoelastic material properties of a hydrogel system during mineralization. Our proof-of-concept system consists of a gelatin hydrogel matrix preloaded with calcium ions and a reservoir of carbonate ions, which diffuse through the gel to initiate mineralization. We found that gels with diffused carbonate show an increase in low frequency energy dissipation, which scales with carbonate concentration and gel pH. Using this signal, and recognizing that mineralization occurs simultaneously with carbonate diffusion in our system, we have mechanoscopically tracked mineral growth in situ, showcasing the potential of rheometry for studying mineralization kinetics in real time