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Fluid Mechanics
Published in Jiro Nagatomi, Eno Essien Ebong, Mechanobiology Handbook, 2018
Tiffany Camp, Richard Figliola
The exact solutions presented can be analogous to many meaningful biomedical applications. As stated in the introduction to this section, differential element analysis of a problem provides detailed information including velocity profile, pressure distribution, and shear stresses in a given flow field. These examples are all based on flows with limitations (laminar, incompressible, steady, Newtonian); however, they can be useful for engineers in biomedical engineering fields. For example, parallel-plate flow chambers are used to study the effects of shear stresses on cells such as in the experiments done by Van Kooten et al. (1992). The cells can be positioned between two plates and exposed to a known flow. Measurements are made accordingly so that the shear stresses levels can be found. Poiseuille's flow can be utilized in a similar manner to find the shear stresses that act on the walls of blood vessels.
An efficient technique in dynamic modeling and analysis of soft fluidic actuator
Published in Mechanics Based Design of Structures and Machines, 2023
Related studies (Breitman, Matia, and Gat 2021; Gamus et al. 2020; Gamus et al. 2018) have almost assumed small deformation for the system behavior. Then, through a simplified linear Euler–Bernoulli beam theorem, a method for dynamic and transverse vibrational modeling was implemented (Matia and Gat 2015). The total deformation of the actuator is considered the linear summation of its response due to internal fluid pressure and external forces which is a controversial simplification of one FSI problem. Their studies present the experimental results to determine the structural response of the actuator due to (i) neglecting the channels’ cross-section changes under the fluid pressure, (ii) neglecting the channels parallel to the length of the beam, (iii) considering constant fluid velocity along the beam, (iv) using a constant Poiseuille coefficient for all fluids, when it changes by fluid viscosity, (v) assuming that the length of every single channel is equal with the beam width, (vi) neglecting from the channel’s effect on the beam second moment of area, and (vii) estimation of the effect of the beam slope on the total displacement of the actuator and some other parameters like channel slope changes, damping coefficient, and cross-sectional area changes which are limited to their experiments.
The effect of assumed boundary conditions on the accuracy of patient-specific CFD arteriovenous fistula model
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2023
Olivia Ng, Sanjiv D. Gunasekera, Shannon D. Thomas, Ramon L. Varcoe, Tracie J. Barber
The Hagen–Poiseuille calculation assumes that flow is laminar, and the cross-sectional area of the tube (vessel) is perfectly cylindrical, in which for most patient-specific cases, an equivalent radius was estimated instead. The former was especially significant given that unsteady flow was often observed at the anastomotic region of the AVF (Bozzetto et al. 2016; Gunasekera et al. 2020b), and the nature of blood flow to be generally turbulent-liked (Saqr et al. 2020). Moreover, blood viscosity was assumed to be constant based on the Hagen–Poiseuille law, which is not the case for blood viscosity that are affected by haematocrit and different composition of blood (Fuchs et al. 2019). Therefore, CFD modelling shown to be able to better capture the effects caused by stenosis better than the Hagen–Poiseuille model.
Ultrasonic characterisation of the binary mixture of 2,3-dichloroaniline with methanol and ethanol
Published in Indian Chemical Engineer, 2022
Mahendra Kumar, Mohd Aftab Khan, Chandreshvar Prasad Yadav, Dharmendra Kumar Pandey, Dhananjay Singh
The viscosity of the present binary mixture was measured by the Poiseuille method [26]. The outflow time with a capillary tube for a known volume of liquid/samples was measured through a digital stopwatch with an accuracy of 0.01 s. The viscosity of the binary mixture is determined using the reference liquid of known viscosity (distil water, 0.8502 mPa s). The experimental viscosity was determined by taking the average of five outflow times. For temperature constancy in the viscosity measurement unit, a water bath thermostat was used with an accuracy of ±0.1°C. The uncertainty in the present viscosity measurement is ± 2.1%.