Springer Science and Business Media LLC

Creating a reliable and accurate Red Blood Cell (RBC) aggregation model for small and midsize arteries and veins is still an active research subject with more in focus with a multi-scale approach including mesoscale effects. Better understanding the RBC aggregation requires a multi-phase and multi-scale approach for simulating blood with Newtonian and non-Newtonian parts. In our proposed work, viscosity, shear rates, phase distributions and volume fractions with a range of hematocrit levels of RBC are calculated using the depletion interaction theory for two-phase blood flow simulation and compared with the numerical and experimental data in literature. In addition, thermal effects are modeled using energy equations and changes in RBC aggregation are studied with respect to thermal variations. Two-phase fluid-fluid model is used including inter-phase momentum exchange. A new shape factor is proposed for the coupling effects on drag and lift forces. Finally, total interaction energy of RBCs, hematocrit levels of blood at varying temperatures and effects of temperature on viscosity and relative apparent viscosity are computed at varying shear rates and compared with the existing data in literature.

Dao động cắt với biên độ lớn (LAOS) được sử dụng để nghiên cứu hành vi bật và dòng chảy của các vật liệu có ứng suất bật. Xét đến các vấn đề trong việc xác định ứng suất bật từ các mô đun động rõ ràng và cường độ hài hòa tương đối bằng cách sử dụng Rheology Biến đổi Fourier, chúng tôi đề xuất một phương pháp mới dựa trên quang phổ tương quan cơ học 2D (2D-MCS) để định lượng ứng suất bật. Chúng tôi đã chứng minh rằng cường độ tự tương quan đồng bộ phi tuyến như là các hàm của biên độ ứng suất/biên độ biến dạng có thể được sử dụng để xác định ứng suất bật một cách rõ ràng từ sự thay đổi của số mũ tỷ lệ. Các ứng suất bật từ phân tích 2D-MCS phù hợp tốt với những kết quả từ các thí nghiệm ramp ứng suất.

The technology of slit-die rheometry came into practice in the early 1960s. This technique enables engineers to measure the pressure drop very precisely along the slit die. Furthermore, slit-die rheometry widens up the measurable shear rate range and it is possible to characterize rheological properties of complicated materials such as wall slipping PVCs and high-filled compounds like long fiber reinforced thermoplastics and PIM-Feedstocks. With the use of slit-die systems in polymer processing machines e.g., Rauwendaal extrusion rheometer, by-pass extrusion rheometer, injection molding machine rheometers, new possibilities regarding rheological characterization of thermoplastics and elastomers at processing conditions near to practice opened up. Special slit-die systems allow the examination of the pressure-dependent viscosity and the characterization of cross-linking elastomers because of melt preparation and reachable shear rates comparable to typical processing conditions. As a result of the viscous dissipation in shear and elongational flows, when performing rheological measurements for high-viscous elastomers, temperature-correction of the apparent values has to be made. This technique was refined over the last years at Montanuniversitaet. Nowadays it is possible to characterize all sorts of rheological complicated polymeric materials under process- relevant conditions with viscosity values fully temperature corrected.

The present article concerns the problem of blood flow through an artery with an axially asymmetric stenosis (constriction). The two-layered macroscopic model consisting of a cell-rich core of suspension of all the erythrocytes described as a particle-fluid suspension (Jeffrey fluid) and a peripheral zone of cell-free plasma (Newtonian fluid). The analytical expressions for flow characteristics such as fluid phase and particle phase velocities, flow rate, wall shear stress, and resistive force are obtained. It is of interest to mention that the magnitudes of wall shear stress and flow resistance increase with red cell concentration but the flow resistance decreases with increasing shape parameter. One of the important observations is that when blood behaves like a Jeffrey fluid, the flowing blood experiences lesser wall shear stress and flow resistance than in the case of blood being characterized as a Newtonian fluid in both the particle-fluid suspension and particle- free flow studies. The rheology of blood as Jeffrey fluid and the introduction of plasma layer thickness cause significant reduction in the magnitudes of the flow characteristics.

This article intends to conduct an analytical simulation for the electroosmosis modulated peristaltic transport of ionic hybrid nano-liquid with Casson model through a symmetric vertical microchannel occupying a homogeneous porous material in the existence of the dominant magnetic field, Hall, and ion-slip currents. The hybrid nano-liquid is acquired by the suspension of silver and silicon dioxide nanoparticles into pure water. The wall slip and convective heating impacts are imposed. The Casson fluid (CF) model is adopted to mimic the rheological behaviour accounting for hybrid nano-liquid. Darcy’s law is applied to evaluate the impact of a porous medium. The Poisson-Boltzmann equation is engaged to accommodate the electric double layer (EDL) in the microchannel. Assumptions of low Reynolds number (LRN), long wavelength (LWL), and Debye-Hückel linearization (DHL) are undertaken to simplify the normalized constitutive equations. Closed-form solutions for the linearized dimensionless resulting equations are achieved by ND-solve code in Mathematica. For a comprehensive physical investigation of the problem under simulation, several graphs are furnished to evaluate the role of emerging thermal and physical parameters in developing the flow patterns and thermal characteristics. Outcomes envisage that Hall, ion-slip, and electro-osmotic parameters have a marked impact on the velocity of the ionic liquid. A decrement in the EDL thickness corresponds to an augmentation in the axial velocity profile in the locality of the channel walls. An increment in radiation parameter results in a demotion in the temperature profile. The pressure gradient is elevated with higher Hall and ion-slip parameters, thermal Grashof number, and electro-osmotic parameter, whereas it is dropped due to higher estimates of Hartmann number. The trapping phenomena under the flow factors are also outlined in brief. The bolus formation is deeply affected by Hall, ion-slip, and electro-osmotic parameters. Outcomes achieved here are expected to shed light on the design and analysis of electro-osmotic pumps, microchannel devices, water filtration and purification processes, DNA analyzers, nanoscale electro-fluid thruster designs in-space propulsion, and many more.