Numerical and Neural Network Analysis of Natural Convection from a Cold Horizontal Cylinder above an Adiabatic Wall

Free convection around cold circular cylinder above an adiabatic plate at steady-state condition has been investigated both numerically and by artificial neural networks. There is a growing demand for a better understanding of free convection from a horizontal cylinder in the areas like air cooling, refrigeration and air conditioning system, etc. Governing equations are solved in some specified cases by finite volume method to generate the database for training the neural network in the range of Rayleigh numbers of 105 to 108 and a range of cylinder distance from adiabatic plate (L/D) of 1/4, 1/2, 1/1, 3/2 and 4/2, thereafter a Multi-Layer Perceptron network is used to capture the behavior of flow and temperature fields and then generalized this behavior to predict the flow and temperature fields for other Rayleigh numbers. Different training algorithms are used and it is found that the back-propagation method with Levenberg-Marquardt learning rule is the best algorithm regarding the faster training procedure. It is observed that ANN can be used more efficiently to determine cold plume and thermal field in less computational time and with an excellent agreement. From obtained results, average Nusselt number of the cylinder investigated to study the effect of adiabatic wall on the isothermal cylinder. It also observed that in spaces farther than L/D = 3/2, average Nusselt number is almost constant, so the affect is renouncement and it works like a cylinder in an infinite environment

Numerical Simulation of the Early Stages of Glaucoma in Human Eye

Background: The eye is one of the most vital organs of human body, and glaucoma is the second-leading cause of blindness after cataracts in the world. However, glaucoma is the leading cause of preventable blindness. The main objective of this study is to investigate intraocular pressure (IOP), stress, strain, and deformation in the retina in early stages of glaucoma. Methods: In this study, a model of the human eye is numerically investigated. The aqueous humor pressure is considered as 30, 35, and 40 mmHg and compared with normal eye pressure. The problem is considered as transient 3D and accurate. Comparison between obtained results shows that the model has been applied. Eye components are also considered with their real properties. Due to the inappreciable effects of turbulence and temperature variation, these effects have been neglected. To determine the pressure field, a two-way fluid-structure interaction is applied, and then, the results are used in a one-way fluid-structure interaction to determine the amount of stress, strain, and deformation of the retina. Results: The maximum deformation in the retina of a glaucoma patient is about 0.33 mm higher than a normal eye, the maximum stress is about 1,300 Pa higher than a normal eye, and the maximum strain is about 0.06 higher than a normal eye. Conclusion: In patients with increased IOP, the amount of deformation in the retina has increased, and the maximum deformation occurs near the optic disc in all cases. Furthermore, maximum stress and maximum strain occur at the place of maximum deformation

Numerical Simulation of Turbulent Airflow and Micro-Particle Deposition in Upper Human Respiratory System

The nasal cavity and sinuses are a component of the upper respiratory system and study the air passage into the upper component of human airway is consequential to amend or remedy deficiency in human respiration cycle. The nose performs many paramount physiological functions, including heating, humidifying and filtering inspired air, as well as sampling air to smell. Aforetime, numerical modeling of turbulent flow in authentic model of nasal cavity, sinus, pharynx and larynx has infrequently been employed. This research has tried to study details of turbulent airflow and particle deposition through all spaces in three-dimensional authentic model of human head which is obtained from computed tomography scan images of a 26-years old female head, neck and chest without any problem in her respiratory system that air can flow them. The particle size in this study was opted to be in the range of 5-30 µm. The particles are tracked through the continuum fluid discretely utilizing the Lagrangian approach