Numeric Analysis of Temperature Distribution in Man using a 3D Human Model

2018 ◽  
Author(s):  
Sipho Mfolozi ◽  
Arnaud Malan ◽  
Tunde Bello-Ochende ◽  
Lorna J. Martin
Keyword(s):  
Body Temperature ◽  
Initial Conditions ◽  
Accurate Determination ◽  
Three Dimensional ◽  
Blood Perfusion ◽  
Human Model ◽  
Post Mortem ◽  
Bioheat Equation ◽  
Death Time ◽  
Analysis Scheme

AbstractPremortem three-dimensional body temperature is the basis on which post-mortem cooling commences. Thermo-numeric analysis of post-mortem cooling for death-time calculation applies pre-mortem three-dimensional body temperature as initial conditions; therefore, an accurate determination of this distribution is important. To date, such prediction is not performed. This paper presents a thermo-numeric analysis method of predicting premortem three-dimensional body temperature in man, to be applied in thermo-numeric analysis of the post-mortem interval using the finite-difference time-domain method. The method applied a Pennes BioHeat Equation modified to linearize organ metabolic and blood flow rates with temperature in a transient thermo-numeric analysis scheme to predict naked three-dimensional temperatures of an MRI-built, 3D human model having 247 segmented organs and 58 categories of material properties under chosen boundary conditions. Organ metabolic heat and blood perfusion rates appropriate for a chosen pre-mortem physical activity, and known organ physical and thermal properties, were assigned to each organ. A steady-state temperature equilibration occurred after 8400 seconds. Predicted organ temperatures were topographically inhomogeneous. Skin temperatures varied between 20.5°C and 42.5°C, liver capsule temperatures were lower than parenchymal, and rectal luminal temperature were uniform.

Human Fall Evaluation Using Motion Capture and Human Modeling

2013 ◽  
Author(s):  
John Wiechel ◽  
Sandra Metzler ◽  
Dawn Freyder ◽  
Nick Kloppenborg
Keyword(s):  
Motion Capture ◽  
Initial Conditions ◽  
Accurate Determination ◽  
Three Dimensional ◽  
Free Fall ◽  
Initial Position ◽  
The Body ◽  
Active Movement ◽  
Injury Biomechanics ◽  
The Individual

Reconstructing the mechanics and determining the cause of a person falling from a height in the absence of witness observations or a statement from the victim can be quite challenging. Often there is little information available beyond the final resting position of the victim and the injuries they sustained. The mechanics of a fall must follow the physics of falling bodies and this physics provides an additional source of information about how the fall occurred. Computational, physics-based simulations can be utilized to model the free-fall portion of the fall kinematics and to analyze biomechanical injury mechanisms. However, an accurate determination of the overall fall kinematics, including the initial conditions and any specific contributions of the person(s) involved, must include the correct position and posture of the individual prior to the fall. Frequently this phase of the analysis includes voluntary movement on the part of the fall victim, which cannot be modeled with simulations using anthropomorphic test devices (ATDs). One approach that has been utilized in the past to overcome this limitation is to run the simulations utilizing a number of different initial conditions for the fall victim. While fall simulations allow the initial conditions of the fall to be varied, they are unable to include the active movement of the subject, and the resulting interaction with other objects in the environment immediately prior to or during the fall. Furthermore, accurate contact interactions between the fall victim and multiple objects in their environment can be difficult to model within the simulation, as they are dependent on the knowledge of material properties of these objects and the environment such as elasticity and damping. Motion capture technology, however, allows active subject movement and behaviors to be captured in a quantitative, three-dimensional manner. This information can then be utilized within the fall simulation to more accurately model the initial fall conditions. This paper presents a methodology for reconstructing fall mechanics using a combination of motion capture, human body simulation, and injury biomechanics. This methodology uses as an example a fall situation where interaction between the fall victim and specific objects in the environment, as well as voluntary movements by the fall victim immediately prior to the accident, provided information that could not be otherwise obtained. Motion capture was first used to record the possible motions of a person in the early stages of the fall. The initial position of the fall victim within the physics based simulation of the body in free fall was determined utilizing the individual body segment and joint angles from the motion capture analysis. The methodology is applied to a real world case example and compared with the actual outcome.

A New Simplified Bioheat Equation for the Effect of Blood Flow on Local Average Tissue Temperature

1985 ◽  
Vol 107 (2) ◽  
pp. 131-139 ◽  
Author(s):  
S. Weinbaum ◽  
L. M. Jiji
Keyword(s):  
Heat Transfer ◽  
Blood Flow ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Blood Perfusion ◽  
Basic Mechanism ◽  
Simple Expression ◽  
Tissue Temperature ◽  
Bioheat Equation ◽  
Countercurrent Exchange

A new simplified three-dimensional bioheat equation is derived to describe the effect of blood flow on blood-tissue heat transfer. In two recent theoretical and experimental studies [1, 2] the authors have demonstrated that the so-called isotropic blood perfusion term in the existing bioheat equation is negligible because of the microvascular organization, and that the primary mechanism for blood-tissue energy exchange is incomplete countercurrent exchange in the thermally significant microvessels. The new theory to describe this basic mechanism shows that the vascularization of tissue causes it to behave as an anisotropic heat transfer medium. A remarkably simple expression is derived for the tensor conductivity of the tissue as a function of the local vascular geometry and flow velocity in the thermally significant countercurrent vessels. It is also shown that directed as opposed to isotropic blood perfusion between the countercurrent vessels can have a significant influence on heat transfer in regions where the countercurrent vessels are under 70-μm diameter. The new bioheat equation also describes this mechanism.

A Quasi-three-dimensional Finite-volume Shallow Water Model for Green Water on Deck

2013 ◽  
Vol 57 (03) ◽  
pp. 125-140
Author(s):  
Daniel A. Liut ◽  
Kenneth M. Weems ◽  
Tin-Guen Yen
Keyword(s):  
Shallow Water ◽  
Finite Volume ◽  
Time Domain ◽  
Degrees Of Freedom ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Green Water ◽  
Water Model ◽  
Ship Motions ◽  
Shallow Water Model

A quasi-three-dimensional hydrodynamic model is presented to simulate shallow water phenomena. The method is based on a finite-volume approach designed to solve shallow water equations in the time domain. The nonlinearities of the governing equations are considered. The methodology can be used to compute green water effects on a variety of platforms with six-degrees-of-freedom motions. Different boundary and initial conditions can be applied for multiple types of moving platforms, like a ship's deck, tanks, etc. Comparisons with experimental data are discussed. The shallow water model has been integrated with the Large Amplitude Motions Program to compute the effects of green water flow over decks within a time-domain simulation of ship motions in waves. Results associated to this implementation are presented.

A Combined Eulerian and Lagrangian Method for Prediction of Evaporating Sprays

2002 ◽  
Vol 124 (3) ◽  
pp. 481-488 ◽  
Author(s):  
M. Burger ◽  
G. Klose ◽  
G. Rottenkolber ◽  
R. Schmehl ◽  
D. Giebert ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Lagrangian Method ◽  
Phase Flow ◽  
Two Phase Flows ◽  
Two Phase ◽  
Lagrangian Methods ◽  
Eulerian Method ◽  
Lagrangian Modeling

Polydisperse sprays in complex three-dimensional flow systems are important in many technical applications. Numerical descriptions of sprays are used to achieve a fast and accurate prediction of complex two-phase flows. The Eulerian and Lagrangian methods are two essentially different approaches for the modeling of disperse two-phase flows. Both methods have been implemented into the same computational fluid dynamics package which is based on a three-dimensional body-fitted finite volume method. Considering sprays represented by a small number of droplet starting conditions, the Eulerian method is clearly superior in terms of computational efficiency. However, with respect to complex polydisperse sprays, the Lagrangian technique gives a higher accuracy. In addition, Lagrangian modeling of secondary effects such as spray-wall interaction enhances the physical description of the two-phase flow. Therefore, in the present approach the Eulerian and the Lagrangian methods have been combined in a hybrid method. The Eulerian method is used to determine a preliminary solution of the two-phase flow field. Subsequently, the Lagrangian method is employed to improve the accuracy of the first solution using detailed sets of initial conditions. Consequently, this combined approach improves the overall convergence behavior of the simulation. In the final section, the advantages of each method are discussed when predicting an evaporating spray in an intake manifold of an internal combustion engine.

Computational Characterization of Passive Fluid Mixing in Microfluidics

Volume 3 ◽  
2004 ◽  
Author(s):  
Erik D. Svensson
Keyword(s):  
Stokes Equations ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Fluid Mixing ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Fluid Systems ◽  
Sensitive Dependence ◽  
Microfluidic Mixers

In this work we computationally characterize fluid mixing in a number of passive microfluidic mixers. Generally, in order to systematically study and characterize mixing in realistic fluid systems we (1) compute the fluid flow in the systems by solving the stationary three-dimensional Navier-Stokes equations or Stokes equations with a finite element method, and (2) compute various measures indicating the degree of mixing based on concepts from dynamical systems theory, i.e., the sensitive dependence on initial conditions and mixing variance.

Effect of Initial Velocity Field on Smoke Diffusion Characteristic in Subway Tunnel

2009 ◽  
Author(s):  
Hui Yang ◽  
Li Jia ◽  
Lixin Yang
Keyword(s):  
Velocity Field ◽  
Field Condition ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Wind Effect ◽  
Diffusion Characteristic ◽  
Subway Tunnel ◽  
Air Velocity ◽  
Initial Field ◽  
Fire Disaster

In this paper, piston wind effect on smoke diffusion characteristic in subway tunnel is studied by using three-dimensional transient computational fluid dynamics (CFD) method. In the first simulation case, fire disaster is simulated with homogeneous resting initial field condition. In the second simulation case, the train’s decelerating process till stopping in the tunnel is simulated for getting three-dimensional tunnel air velocity field distribution. Then the final heterogeneous air velocity field when the train stops in the tunnel is taken as initial field condition and the same fire scenario as the first case is simulated again. The data obtained under both initial conditions are compared by detecting people evacuation safety and the influence of initial air velocity field is analyzed. The results show that the inertial air velocity field caused by train’s movement has significant influence on smoke diffusion at the first few minutes of fire disaster, which is the key time for people’s evacuation. The adopted method in this paper and the simulation result could be used in establishing more effective subway fire evacuation plan.

Fanno Design of Blow-Off Lines in Heavy Duty Gas Turbine

2013 ◽  
Author(s):  
Marco Cioffi ◽  
Enrico Puppo ◽  
Andrea Silingardi
Keyword(s):  
Gas Turbines ◽  
Gas Flow ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Design Procedure ◽  
Flow Equation ◽  
Heavy Duty ◽  
Cross Sectional ◽  
Pipe Length ◽  
Choked Flow

In typical heavy duty gas turbines the multistage axial compressor is provided with anti-surge pipelines equipped with on-off valves (blow-off lines), to avoid dangerous flow instabilities during start-ups and shut-downs. Blow-off lines show some very peculiar phenomena and somewhat challenging fluid dynamics, which require a deeper regard. In this paper the blow-off lines in axial gas turbines are analyzed by adopting an adiabatic quasi-unidimensional model of the gas flow through a pipe with a constant cross-sectional area and involving geometrical singularities (Fanno flow). The determination of the Fanno limit, on the basis of the flow equation and the second principle of thermodynamics, shows the existence of a critical pipe length which is a function of the pipe parameters and the initial conditions: for a length greater than this maximum one, the model requires a mass-flow reduction. In addition, in the presence of a regulating valve, so-called multi-choked flow can arise. The semi-analytical model has been implemented and the results have been compared with a three-dimensional CFD analysis and cross-checked with available field data, showing a good agreement. The Fanno model has been applied for the analysis of some of the actual machines in the Ansaldo Energia fleet under different working conditions. The Fanno tool will be part of the design procedure of new machines. In addition it will define related experimental activities.

scholarly journals Prediction human skin temperature in comfort level

2019 ◽  
Vol 1 (3) ◽  
pp. 1-4
Author(s):  
Zaina Norhallis Zainol ◽  
Masine Md. Tap ◽  
Haslinda Mohamed Kamar
Keyword(s):  
Thermal Comfort ◽  
Skin Temperature ◽  
Human Skin ◽  
Blood Perfusion ◽  
Comfort Level ◽  
Working Environment ◽  
Percentage Error ◽  
Bioheat Equation ◽  
Acceptable Error ◽  
Human Arm

Thermal comfort is the human subject perceive satisfaction to the work environment. The thermal comfort need to be achieve towards productive working environment. The comfort level of the subject is affected by the human skin temperature. To assess the skin temperature with the sorrounding by conducting human experiment in the climatic chamber. It is rigorous and complex experiment.This study was developed to predict human skin temperature in comfort level with the finite element method and the bioheat equation. The bioheat equation is a consideration of metabolic heat generation and the blood perfusion to solve heat transfer of the living tissue. It is to determine the skin temperature focussing at the human arm. From the study, it is found that the predicted skin temperature value were in well agreement with the experimental results. The percentage error insignificant with acceptable error of 1.05%.

scholarly journals PARALLEL COMPUTATIONS IN STUDIES OF DEPENDENCE OF GAS DYNAMIC PARAMETERS OF UPWARD SWIRLING FLOW OF GAS ON BLOWING VELOCITY

2016 ◽  
pp. 92-97
Author(s):  
R. E. Volkov ◽  
A. G. Obukhov
Keyword(s):  
Stokes Equations ◽  
Swirling Flow ◽  
Initial Conditions ◽  
Exact Analytical Solution ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Heat Conducting ◽  
Computational Domain ◽  
Navier Stokes Equations ◽  
Gas Dynamic

The rectangular parallelepiped explicit difference schemes for the numerical solution of the complete built system of Navier-Stokes equations. These solutions describe the three-dimensional flow of a compressible viscous heat-conducting gas in a rising swirling flows, provided the forces of gravity and Coriolis. This assumes constancy of the coefficient of viscosity and thermal conductivity. The initial conditions are the features that are the exact analytical solution of the complete Navier-Stokes equations. Propose specific boundary conditions under which the upward flow of gas is modeled by blowing through the square hole in the upper surface of the computational domain. A variant of parallelization algorithm for calculating gas dynamic and energy characteristics. The results of calculations of gasdynamic parameters dependency on the speed of the vertical blowing by the time the flow of a steady state flow.

scholarly journals INTEGRATION OF COMPLEMENTARY BIOMARKERS IN PATIENTS WITH FIRST EPISODE PSYCHOSIS: RESEARCH PROTOCOL OF A PROSPECTIVE FOLLOW UP STUDY

2019 ◽  
Author(s):  
Petra ◽  
Martina Rojnic Kuzman ◽  
Porin Makaric ◽  
Dina Bosnjak Kuharic ◽  
Ivana Kekin ◽  
...  
Keyword(s):  
Genome Wide Association Study ◽  
Single Photon ◽  
Single Gene ◽  
Photon Emission ◽  
Blood Perfusion ◽  
First Episode ◽  
Emission Computed Tomography ◽  
Healthy Controls ◽  
Post Mortem

In this project, we recruited a sample of 150 patients with first episode of psychosis with schizophrenia features (FEP) and 100 healthy controls. We assessed the differences between these two groups, as well as the changes between the acute phase of illness and subsequent remission among patients over 18-month longitudinal follow-up. The assessments were divided into four work packages (WP): WP1- psychopathological status, neurocognitive functioning and emotional recognition; WP2- stress response measured by saliva cortisol during a stress paradigm; cerebral blood perfusion in the resting state (with single photon emission computed tomography (SPECT) and during activation paradigm (with Transcranial Ultrasonography Doppler (TCD); WP3-post mortem analysis in histologically prepared human cortical tissue of post mortem samples of subjects with schizophrenia in the region that synaptic alteration was suggested by WP1 and WP2; WP4- pharmacogenetic analysis (single gene polymorphisms and genome wide association study (GWAS). We expect that the analysis of these data will identify a set of markers that differentiate healthy controls from patients with FEP, and serve as an additional diagnostic tool in the first episode of psychosis, and prediction tool which can be then used to help tailoring individualized treatment options. In this paper, we describe the project protocol including aims and methods and provide a brief description of planned post mortem studies and pharmacogenetic analysis.

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