A short review of some reference solutions for the magnetohydrodynamic flow of blood is proposed in this paper. We present in details the solutions of Hartmann (1937), of Vardanyan (1973) and of Sud et al. (1974). In ...A short review of some reference solutions for the magnetohydrodynamic flow of blood is proposed in this paper. We present in details the solutions of Hartmann (1937), of Vardanyan (1973) and of Sud et al. (1974). In each case, a comparison is provided with the corresponding solution for the flow without any external magnetic field, namely Poiseuille (plane or cylindrical) and Womersley. We also present a synopsis of some other solutions for people who would like to go further in this topic. The interest in MHD flow of blood may be motivated by many reasons, such as Magnetic Resonance Imaging (MRI), Pulse Wave Velocity measurement, magnetic drug targeting, tissue engineering, mechanotransduction studies, and blood pulse energy harvesting… These fundamental solutions should also be used as particular limiting cases to validate any proposed more elaborated solutions or to validate computer codes.展开更多
Background: Hemodynamics is a practical and complicated theoretical problem. The aim of this paper is to analyze the characteristics of blood pressure in the cardiovascular system changing with the mechanical paramete...Background: Hemodynamics is a practical and complicated theoretical problem. The aim of this paper is to analyze the characteristics of blood pressure in the cardiovascular system changing with the mechanical parameters of blood vessels and the storage of some visceral organs. Method: The fluid network model was used for the study. The cardiovascular system was modeled as a system consisting of 20 segments of vessels. The main controlling parameters were determined first by using dimensional analysis. Then the responses of blood pressure of each segment of vessels were analyzed by changing the controlling parameters. Results: The parameters of the blood vessel of brain have the least influence on the pressures of other parts. The pressures of the system of blood vessels will decrease if some blood is stored in the liver or the abdominal vein system. Vice versa. The effects of regulation of blood on the variation of blood pressure are larger than the other controlling parameters. Conclusions: The controlling parameters of the abdominal aorta and ascending aorta affect greatly the blood pressure of each vessel.展开更多
Oscillatory flow facilitates gas exchange in human respiration system. In the present study, both numerical calculation and PIV (Particle Image Velocimetry) measurement indicate that, under the application of HFOV (Hi...Oscillatory flow facilitates gas exchange in human respiration system. In the present study, both numerical calculation and PIV (Particle Image Velocimetry) measurement indicate that, under the application of HFOV (High Frequency Oscillatory Ventilation), apparent steady streaming is caused and augmented in distal airways by the continuous oscillation, i.e., the core air moves downwards and the peripheral air evacuates upwards within bronchioles. The net flow of steady streaming serves to overcome the lack of tidal volume in HFOV and delivers fresh air into deeper lung region. Also, numerical calculations reveal that the intensity of steady streaming is mainly influenced by the geometry of airways with provided oscillatory frequency and tidal volume, and it rises with Re and Wo up to a Re of about 124 and Wo of about 5. Steady streaming is considered as an important factor for the ventilation efficiency of HFOV.展开更多
文摘A short review of some reference solutions for the magnetohydrodynamic flow of blood is proposed in this paper. We present in details the solutions of Hartmann (1937), of Vardanyan (1973) and of Sud et al. (1974). In each case, a comparison is provided with the corresponding solution for the flow without any external magnetic field, namely Poiseuille (plane or cylindrical) and Womersley. We also present a synopsis of some other solutions for people who would like to go further in this topic. The interest in MHD flow of blood may be motivated by many reasons, such as Magnetic Resonance Imaging (MRI), Pulse Wave Velocity measurement, magnetic drug targeting, tissue engineering, mechanotransduction studies, and blood pulse energy harvesting… These fundamental solutions should also be used as particular limiting cases to validate any proposed more elaborated solutions or to validate computer codes.
文摘Background: Hemodynamics is a practical and complicated theoretical problem. The aim of this paper is to analyze the characteristics of blood pressure in the cardiovascular system changing with the mechanical parameters of blood vessels and the storage of some visceral organs. Method: The fluid network model was used for the study. The cardiovascular system was modeled as a system consisting of 20 segments of vessels. The main controlling parameters were determined first by using dimensional analysis. Then the responses of blood pressure of each segment of vessels were analyzed by changing the controlling parameters. Results: The parameters of the blood vessel of brain have the least influence on the pressures of other parts. The pressures of the system of blood vessels will decrease if some blood is stored in the liver or the abdominal vein system. Vice versa. The effects of regulation of blood on the variation of blood pressure are larger than the other controlling parameters. Conclusions: The controlling parameters of the abdominal aorta and ascending aorta affect greatly the blood pressure of each vessel.
文摘Oscillatory flow facilitates gas exchange in human respiration system. In the present study, both numerical calculation and PIV (Particle Image Velocimetry) measurement indicate that, under the application of HFOV (High Frequency Oscillatory Ventilation), apparent steady streaming is caused and augmented in distal airways by the continuous oscillation, i.e., the core air moves downwards and the peripheral air evacuates upwards within bronchioles. The net flow of steady streaming serves to overcome the lack of tidal volume in HFOV and delivers fresh air into deeper lung region. Also, numerical calculations reveal that the intensity of steady streaming is mainly influenced by the geometry of airways with provided oscillatory frequency and tidal volume, and it rises with Re and Wo up to a Re of about 124 and Wo of about 5. Steady streaming is considered as an important factor for the ventilation efficiency of HFOV.
