No abstract

Computational fluid dynamics (CFD) simulations with machine learning Algorithms (MLA) is becoming increasingly popular as the combination reduces the computational time of the CFD simulations required for classifying, predicting, or optimising the impact of geometrical and physical variables of a specific study. The main target of drug delivery studies is predicting the optimum particle diameter for targeting particular locations in the lung to achieve a desired therapeutic effect. In addition, the main goal of molecular dynamics studies is investigating particle-lung interaction through given particle properties. Therefore, this study combines the two by numerically determining the optimum particle diameter required to obtain an ideal striking velocity magnitude and impact time inside an acinar part of the lung. At first, the striking velocity magnitudes and time for impact (two independent properties) of three different particle diameters () are computed using CFD simulations. Then, machine learning classifiers determine the particle diameter corresponding to these two independent properties. In this study, two cases are compared: A healthy acinus where a surfactant layer covers the inner surface of the alveoli providing low air-liquid surface tension (LST) values), and a diseased acinus where only a water layer covers the surface causing high surface tension (HST) values ). Results showed that all three particle diameters attain larger velocities and smaller impact times in a diseased acinus than in a healthy one. In both cases, the particles acquire the smallest velocities and longest impact times, and the particles possess the largest velocities and shortest impact times.

No abstract

Following the emergence of many blood transfusion-associated diseases, novel passive cell separation technologies, such as microfluidic devices, are increasingly designed and optimized to separate red blood cells (RBCs) and white blood cells (WBCs) from whole blood. These systems allow for the rapid diagnosis of diseases without relying on complicated and expensive hematology instruments such as flow microscopes, coagulation analyzers, and cytometers. The inertia effect and the impact of intrinsic hydrodynamic forces, the Dean drag force (FD), and the inertial lift force (FL) on the migration of particles within curved and complex confined channels have been explored theoretically, computationally, and experimentally. This study aimed to optimize the dimensions of a microfluidic channel for fast particle propagation and separation. Several spiral geometries with different cross-sections were tested using computational fluid dynamics (CFD) to separate two particle types representing RBCs and WBCs. The chosen three geometries consist of a single inlet, two outlets, and three spiral turns, each having a different cross-sectional height (120, 135, and 150 µm). Particle separation was successfully achieved in the 135 µm-height microchannel, while other microchannels demonstrated mixed particle types at the outlets.

Heat transfer between inhaled hot/cool air and the lung surface within the human respiratory system is an intriguing topic that has not received enough attention. The lung can be considered as an in-vivo heat exchanger, balancing the inhaled air temperature by lowering the hot air temperature and increasing the cool air temperature. The current work studies the unsteady and incompressible airflow motion and heat transfer during inhalation between the surface of the lungs (37 ◦C) and the inhaled cool air (25 ◦C) in one case and inhaled hot air (43 ◦C) in another. Computerized tomography scan (CT-Scan) images of the lung were processed to generate the airway geometry consisting of 16 generations. The mesh generation was carried out using Ansys Meshing. The SST turbulent model was employed in Ansys Fluent 20.2 to model the air/lung convective volume heat transfer utilizing a realistic breathing velocity profile. Temperature streamlines, lung volume temperatures, surface heat flux, and surface temperatures on all 16 generations were produced for both cases during the breathing cycle of 4.75 s. Several conclusions were made by studying and comparing the two cases. First, heat transfer between inhaled hot or cool air and the lung surface mainly occurred in the first few generations. Second, airflow temperature patterns are dependent on the inlet breathing velocity profile. Third, the lung volume temperature change directly correlates to the temperature difference between air and the lung surface. Finally, the surface heat flux strongly depended on the heat transfer coefficient.