Presence of eyelid on anterior ocular surface and its thermal effects play significant role in maintaining eye temperature. In most of the literatures of thermal modeling in human eye, the eyelid is not considered as an eye component. In this paper, finite element model is developed to investigate the thermal effects of eyelid closure and opening in human eye. Based on different properties and parameter values reported in literatures, the bio-heat transfer process is simulated and compared with experimental results in steady and transient state cases. The sensitivity analysis using various ambient temperatures, evaporation rates, blood temperatures and lens thermal conductivities is carried out. The temperature values so obtained in open eye show a good agreement with past results. The closure of eyelid is found to increase/decrease the eye temperature significantly than its opening, when the parameter values are considered to be at extreme.
Blinking is regarded as the continuous interrupted eyelid closure or opening and its thermal effect will compromise between these two. During a blink, the heat loss via convection, radiation and tear evaporation from cornea is prevented, warm tear is layered across corneal surface and the vessels of the palpebral conjunctiva provide heat to anterior eye. In most of the thermal models in human eye that are found in literatures, effect of blinking is not included, simulation is carried out only in open eye. Thus, in this paper, thermal effects of blinking are investigated using one-dimensional finite element method in transient state case. The bio-heat transfer process is simulated during different blinking rates, lid closure and opening. The simulation is carried out using normal and extreme values of ambient temperatures, blood temperatures, evaporation rates, blood perfusion rates, and lens thermal conductivities. Blinking is found to increase corneal and lens temperature by 1.29 • C and 0.78 • C respectively when compared to open eye. The results obtained from this model are useful in predicting temperature distribution in different laser eye surgeries, hyperthermia and cryosurgery treatment of eyelid carcinoma, choroidal melanoma and can be used for diagnosing temperature-related diseases.
Thin film flow is an important theme in fluid mechanics and has many industrial applications. These flows can be observed in oil refinement process, laser cutting, and nuclear reactors. In this theoretical study, we explore thin film flow of non-Newtonian Johnson–Segalman fluid on a vertical belt in fractional space in lifting and drainage scenarios. Modelled fractional-order boundary value problems are solved numerically using the homotopy perturbation method along with Caputo definition of fractional derivative. In this study, instantaneous and average velocities and volumetric flux are computed in lifting and drainage cases. Validity and convergence of homotopy-based solutions are confirmed by finding residual errors in each case. Moreover, the consequences of different fractional and fluid parameters are graphically studied on the velocity profile. Analysis shows that fractional parameters have opposite effects of the fluid velocity.
The thermoregulation of human female body is influenced by hormonal and physiological changes in the body during the menstrual cycle. The fluctuation of estrogen and progesterone hormones, release in the follicular phase and the luteal phase of menstrual cycle, respectively play an important role in the growth of breast ducts and lobules (milk glands). The imbalance of these hormones causes breast tumors/cysts. The body core temperature, blood perfusion and metabolism rate are higher in the luteal phase than the follicular phase of menstrual cycle. In the present work, a tumor/cyst is assumed to be in the glandular layer. A two-dimensional Pennes bioheat equation is solved to find the temperature variation in breast tissue with and without tumor/cyst during the menstrual cycle by using the finite element method. The results show that the temperature of each layer of breast tissue in the luteal phase is higher than the follicular phase in the case of normal breast, tumorous breast and breast with cyst.
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