Two-dimensional finite difference model to study temperature distribution in SST regions of human limbs immediately after physical exercise in cold climate

2015 ◽  
Vol 04 (01) ◽  
pp. 1550002
Author(s):  
Babita Kumari ◽  
Neeru Adlakha
Keyword(s):  
Thermal Stress ◽  
Heat Exchange ◽  
Temperature Distribution ◽  
Finite Difference ◽  
Physical Exercise ◽  
Peripheral Region ◽  
Cold Climate ◽  
The Body ◽  
Cylindrical Shape ◽  
Two Dimensional

Thermoregulation is a complex mechanism regulating heat production within the body (chemical thermoregulation) and heat exchange between the body and the environment (physical thermoregulation) in such a way that the heat exchange is balanced and deep body temperatures are relatively stable. The external heat transfer mechanisms are radiation, conduction, convection and evaporation. The physical activity causes thermal stress and poses challenges for this thermoregulation. In this paper, a model has been developed to study temperature distribution in SST regions of human limbs immediately after physical exercise under cold climate. It is assumed that the subject is doing exercise initially and comes to rest at time t = 0. The human limb is assumed to be of cylindrical shape. The peripheral region of limb is divided into three natural components namely epidermis, dermis and subdermal tissues (SST). Appropriate boundary conditions have been framed based on the physical conditions of the problem. Finite difference has been employed for time, radial and angular variables. The numerical results have been used to obtain temperature profiles in the SST region immediately after continuous exercise for a two-dimensional unsteady state case. The results have been used to analyze the thermal stress in relation to light, moderate and vigorous intensity exercise.

TWO-DIMENSIONAL FINITE ELEMENT MODEL TO STUDY THERMO BIOMECHANICS IN PERIPHERAL REGIONS OF HUMAN LIMBS DUE TO EXERCISE IN COLD CLIMATE

2017 ◽  
Vol 17 (01) ◽  
pp. 1750002 ◽  
Author(s):  
BABITA KUMARI ◽  
NEERU ADLAKHA
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Physical Exercise ◽  
Peripheral Region ◽  
Cold Climate ◽  
Two Dimensional ◽  
Human Beings ◽  
Thermal Dynamics ◽  
Thermal Injuries ◽  
The Impact

Human beings are equipped with thermo sensitivity, thermoregulation and thermo protection for maintaining the structure and function of their body organs. The thermoregulatory responses and disturbances caused by physical activity in thermo biomechanics of human body organs are not well understood. The mechanism of thermoregulation exhibits a beautiful coordination of biophysical process in order to balance distribution caused by a biothermal system due to physical exercise and other abnormal conditions. In view of above, a model has been developed to study the thermal dynamics in peripheral region of human limbs immediately after exercise under cold climatic conditions. The human limb is assumed to be of cylindrical shape. The peripheral region of limb is divided into three natural components namely epidermis, dermis and subdermal tissues. Appropriate boundary conditions have been framed based on the physical condition of the problem. Finite difference has been employed for time variable and the finite element method is employed along radial and angular direction. The numerical results have been used to obtain temperature profiles in the peripheral region immediately after continuous exercise for a two-dimensional unsteady state case. These results have been used to analyze the thermal disturbances caused by the different intensities of physical exercise in the peripheral region of human limbs. Such a model can be developed to study the generated thermal information which can be useful to biomedical science to analyze the impact of thermal stress on mechanism of thermoregulation causing thermal injuries like heat cramps, heat exhaustion and heat stroke. The results give the idea about the capacity of biothermo mechanisms of human limbs in counting balance. The thermal stress is caused by different intensities of physical exercise. These results can be useful for the biomedical scientists to understand the thermal discomfort caused by different intensities of physical exercise and the time period of rest required to overcome discomfort. Further, the result can be useful to biomedical scientists for developing protocols for physical exercise and rest required by the subject for different intensities of physical exercise and prevent thermal injuries in the workers and sportsmen.

Two-dimensional finite element model to study temperature distribution in peripheral regions of extended spherical human organs involving uniformly perfused tumors

2015 ◽  
Vol 08 (06) ◽  
pp. 1550074 ◽  
Author(s):  
Akshara Makrariya ◽  
Neeru Adlakha
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Finite Element Model ◽  
Metabolic Activity ◽  
Element Model ◽  
The Body ◽  
Tissue Response ◽  
Two Dimensional ◽  
Human Breast ◽  
Peripheral Regions

Temperature as an indicator of tissue response is widely used in clinical applications. In view of above a problem of temperature distribution in peripheral regions of extended spherical organs of a human body like, human breast involving uniformly perfused tumor is investigated in this paper. The human breast is assumed to be spherical in shape with upper hemisphere projecting out from the trunk of the body and lower hemisphere is considered to be a part of the body core. The outer surface of the breast is assumed to be exposed to the environment from where the heat loss takes place by conduction, convection, radiation and evaporation. The heat transfer from core to the surface takes place by thermal conduction and blood perfusion. Also metabolic activity takes place at different rates in different layers of the breast. An elliptical-shaped tumor is assumed to be present in the dermis region of human breast. A finite element model is developed for a two-dimensional steady state case incorporating the important parameters like blood flow, metabolic activity and thermal conductivity. The triangular ring elements are employed to discretize the region. Appropriate boundary conditions are framed using biophysical conditions. The numerical results are used to study the effect of tumor on temperature distribution in the region.

The Effects of Thermocouple Materials and Insulating Mica in an Erodable Surface Thermocouple

2008 ◽  
Author(s):  
Alan Grech ◽  
Tonio Sant ◽  
Mario Farrugia
Keyword(s):  
Heat Flux ◽  
Thermal Properties ◽  
Finite Difference ◽  
The Body ◽  
Two Dimensional ◽  
Difference Model ◽  
Dimensional Effects ◽  
Surface Thermocouple ◽  
Simulation Results ◽  
Transient Heat Flux

A finite-difference model of a surface thermocouple (erodable-ribbon type) of a heat flux sensor was built to analyze the transient response of the thermal junction and the two-dimensional effects created by the insulation between the thermocouple materials and the body material of the sensor. Such transient heat flux sensors have previously been used for measurements in internal combustion engines. It is commonly assumed that the heat transfer within these devices is one-dimensional even though the sensors are constructed from at least two different materials. It is common practice to calculate the transient heat flux using properties of body material and this leads to a substantial error as demonstrated by the model. With these sensors, low thermal capacity thermocouple junctions are formed near the surface by abrasion and response times as low as 30μs have been reported. Experiments were performed on an E type surface thermocouple heated at 11W by means of a copper vapor laser pulsating at 10kHz. Measurement of surface thermocouple temperature was performed at a 100kHz sampling rate. A finite-difference model was used to analyze the response of these sensors to the pulsed laser heating operating at 10 kHz. The insulation between the thermocouples and the body material was mica and the body material was AISI 316 stainless steel. The experimental measurements and simulation results are reported in this work. The analysis and comparison of experimental and simulation results showed that for such thermocouples two-dimensional effects exist due to the presence of mica sheets. The temperature decay between pulses was better matched using thermal properties of mica sheets rather than the thermal properties of the body material. However the body material still dominates the temperature swing of the thermocouple junction.

Analytical Investigation of Microwave Heating

2010 ◽  
Author(s):  
Mohammad Robiul Hossan ◽  
Prashanta Dutta
Keyword(s):  
Temperature Distribution ◽  
Analytical Solution ◽  
Electric Field ◽  
Microwave Heating ◽  
Analytical Investigation ◽  
The Body ◽  
Limiting Factor ◽  
Cylindrical Shape ◽  
Closed Form Analytical Solution ◽  
Poynting Theorem

Microwave heating is very popular and widely used for warming up foodstuffs quickly. However, non-uniform temperature distribution obtained from microwave heating is a major limiting factor for its application outside the food industry. The rapid decay of incident microwave and the potential existence of standing wave are responsible for non-uniform heating. Therefore, it is important to study the coupling between microwave propagation and energy transfer in the system to predict temperature distribution. In this paper, a closed-form analytical solution is presented to predict the temperature distribution within a cylindrical shape foodstuff under microwave heating by solving an unsteady energy equation. The simplified Maxwell’s equation is solved for electric field distribution; Poynting theorem is employed to calculate microwave power from electric field. The results show that the temperature in the body is very sensitive to size and time. This analytical solution can be used to investigate the influence of various parameters on microwave heating.

The effect of the temperature distribution along the perimeter of the boundary on the the flow in the convective Rayleigh-Benard cell

2011 ◽  
Vol 8 (1) ◽  
pp. 116-123
Author(s):  
V.L. Malyshev ◽  
E.F. Moiseeva ◽  
K.V. Moiseyev
Keyword(s):  
Natural Convection ◽  
Heat Exchange ◽  
Temperature Distribution ◽  
Incompressible Fluid ◽  
Viscous Incompressible Fluid ◽  
Maximum Speed ◽  
Two Dimensional ◽  
Rayleigh Benard ◽  
Dimensional Cell

This paper is devoted to the study of the natural convection of a viscous incompressible fluid in a two-dimensional cell with combined vertical and horizontal heating in symmetrical and asymmetrical cases; investigation of the dependence of the maximum speed and intensity of heat exchange on different heating regimes.

Three-dimensional finite element model to study temperature distribution in peripheral layers of human limbs immediately after physical exercise

2017 ◽  
Vol 10 (04) ◽  
pp. 1750053 ◽  
Author(s):  
Babita Kumari ◽  
Neeru Adlakha
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Physical Exercise ◽  
Finite Element Model ◽  
Three Dimensional ◽  
Element Model ◽  
The Body ◽  
Dimensional Finite Element ◽  
Human Limb ◽  
Three Dimensional Finite Element

The physical exercise imposes challenges on the human thermoregulatory system, as heat exchange between the body and environment is substantially impaired, which can lead to decrease in performance and increased risk of heat illness. In view of above a three-dimensional finite element model is proposed to study the effect of different intensities of physical exercise on temperature distribution in peripheral regions of human limbs under moderate climatic conditions. Human limb is assumed to have a cylindrical cross-section. The peripheral region of the human limb is divided into three natural components, namely epidermis, dermis and subdermal tissues. The model incorporates the effect of important physiological parameters like blood mass flow rate, metabolic heat generation, and thermal conductivity of the tissues. Appropriate boundary conditions have been framed based on the physical conditions of the problem. The model is transformed into the discretized variational form and finite element method (FEM) has been employed to obtain the solution. The numerical results have been used to obtain the temperature profiles in the region immediately after exercise for an unsteady state case. The thermal information generated from the model can be useful for developing protocols for improving performance of sportsmen, military persons and labor-intensive workers.

A method of convergence for finite difference thermal stress computation in axially symmetrical bodies

1967 ◽  
Vol 2 (4) ◽  
pp. 332-340
Author(s):  
C L Chow ◽  
R Hoyle
Keyword(s):  
Thermal Stress ◽  
Temperature Distribution ◽  
Finite Difference ◽  
Rate Of Convergence ◽  
Thermal Load ◽  
Turbine Rotor ◽  
Transient Temperature ◽  
Rapid Rate ◽  
Transient Temperature Distribution ◽  
Stress Computation

The most general axially symmetrical thermal load is one in which a transient temperature distribution, varying axially and radially, is applied to an axially symmetrical system with an irregular axial boundary. When the thermal stress equations are applied to such a system, using the conventional Gauss-Siedel or Liebmann method, severe oscillation has been experienced making convergence impossible to achieve. The authors present in this paper a method which not only converts a diverging solution but also yields a rapid rate of convergence. This method has been successfully applied to the problem of a steam turbine rotor.

Modelling of Moisture Movement in Wood during Outdoor Storage

2001 ◽  
Vol 6 (2) ◽  
pp. 3-14 ◽  
Author(s):  
R. Baronas ◽  
F. Ivanauskas ◽  
I. Juodeikienė ◽  
A. Kajalavičius
Keyword(s):  
Experimental Data ◽  
Finite Difference ◽  
Climatic Conditions ◽  
Two Dimensional ◽  
Moisture Movement ◽  
Finite Difference Technique ◽  
Long Term Storage ◽  
Space Formulation ◽  
Term Storage

A model of moisture movement in wood is presented in this paper in a two-dimensional-in-space formulation. The finite-difference technique has been used in order to obtain the solution of the problem. The model was applied to predict the moisture content in sawn boards from pine during long term storage under outdoor climatic conditions. The satisfactory agreement between the numerical solution and experimental data was obtained.

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