Energy Considerations in the Spreading of LNG on Sea Water

2008 ◽  
Author(s):  
A. Subramani ◽  
S. Jayanti
Keyword(s):  
Heat Transfer ◽  
Sea Water ◽  
Current Model ◽  
Theoretical Models ◽  
Effect Of Temperature ◽  
Test Case ◽  
Hazardous Substance ◽  
Temperature Dependent ◽  
One Dimensional ◽  
Conventional Models

The spreading of an accidental spill of Liquefied Natural Gas (LNG) on sea water has been studied for many years and several theoretical models have been proposed and successfully used. Many modeling techniques have been used by researchers for the spreading of LNG. However, most of these neglect the heat transfer aspects related to the spreading, and the effect of temperature dependent properties such as density, thermal conductivity and specific heat of LNG is not included in the analysis. In the present study, this situation is redressed by including the depth-averaged energy equation in a one-dimensional model of the spreading of LNG on sea water. The thermophysical and transport properties of the fluid are made temperature-dependent and heat transfer to the pool from the water below and the flame above are included. The resulting set of coupled one-dimensional mass, radial momentum and energy balance equations are solved numerically using an explicit, second order-accurate finite difference method-based discretization of the governing equations. Results obtained in the present study show that the incorporation of the variable properties gives significantly improved predictions over conventional models. The predicted results are compared with the experimental results of Raj et al [1], and with a conventional, constant-properties model of Fay [2] for the test case #12. Excellent agreement is found between the current model predictions and the experimental data while the conventional model overpredicts the pool diameter for longer times. It is demonstrated that the present approach is inherently capable of distinguishing between the spreading of different LNG mixtures, and can therefore be readily extended to the analysis of the accidental spill of any other hazardous substance.

Sensitivity Analysis of One-Dimensional Heat Transfer in Tissue With Temperature-Dependent Perfusion

1997 ◽  
Vol 119 (1) ◽  
pp. 77-80 ◽  
Author(s):  
C. R. Davies ◽  
G. M. Saidel ◽  
H. Harasaki
Keyword(s):  
Heat Transfer ◽  
Sensitivity Analysis ◽  
Heated Surface ◽  
Experimental Studies ◽  
Total Artificial Heart ◽  
Tissue Temperature ◽  
Model Parameters ◽  
Temperature Dependent ◽  
One Dimensional

Design criteria for implantable, heat-generating devices such as the total artificial heart require the determination of safe thresholds for chronic heating. This involves in-vivo experiments in which tissue temperature distributions are obtained in response to known heat sources. Prior to experimental studies, simulation using a mathematical model can help optimize the design of experiments. In this paper, a theoretical analysis of heat transfer is presented that describes the dynamic, one-dimensional distribution of temperature from a heated surface. Loss of heat by perfusion is represented by temperature-independent and temperature-dependent terms that can reflect changes in local control of blood flow. Model simulations using physiologically appropriate parameter values indicate that the temperature elevation profile caused by a heated surface adjacent to tissue may extend several centimeters into the tissue. Furthermore, sensitivity analysis indicates the conditions under which temperature profiles are sensitive to changes in thermal diffusivity and perfusion parameters. This information provides the basis for estimation of model parameters in different tissues and for prediction of the thermal responses of these tissues.

Solving One-Dimensional Partial Differential Equations

2021 ◽  
pp. 191-215
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Partial Differential Equations ◽  
Differential Equations ◽  
Boundary Conditions ◽  
Material Properties ◽  
Final Part ◽  
Temperature Dependent ◽  
Partial Differential ◽  
One Dimensional

This chapter describes the pdepe command, which is used to solve spatially one-dimensional partial differential equations (PDEs). It begins with a description of the standard forms of PDEs and its initial and boundary conditions that the pdepe solver uses. It is shown how various PDEs and boundary conditions can be represented in standard forms. Applications to the mechanics are presented in the final part of the chapter. They illustrate how to solve: heat transfer PDE with temperature dependent material properties, startup velocities of the fluid flow in a pipe, Burger's PDE, and coupled FitzHugh-Nagumo PDE.

scholarly journals Effect of Temperature-Dependent Variable Viscosity on Magnetohydrodynamic Natural Convection Flow along a Vertical Wavy Surface

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Nazma Parveen ◽  
Md. Abdul Alim
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Friction Coefficient ◽  
Skin Friction ◽  
Variable Viscosity ◽  
Skin Friction Coefficient ◽  
Effect Of Temperature ◽  
Convection Flow ◽  
Temperature Dependent ◽  
Natural Convection Flow

The effect of temperature dependent variable viscosity on magnetohydrodynamic (MHD) natural convection flow of viscous incompressible fluid along a uniformly heated vertical wavy surface has been investigated. The governing boundary layer equations are first transformed into a nondimensional form using suitable set of dimensionless variables. The resulting nonlinear system of partial differential equations are mapped into the domain of a vertical flat plate and then solved numerically employing the implicit finite difference method, known as Keller-box scheme. The numerical results of the surface shear stress in terms of skin friction coefficient and the rate of heat transfer in terms of local Nusselt number, the stream lines and the isotherms are shown graphically for a selection of parameters set consisting of viscosity parameter (), magnetic parameter (), and Prandtl number (Pr). Numerical results of the local skin friction coefficient and the rate of heat transfer for different values are also presented in tabular form.

The Effect of Temperature on the Material Damping of Graphite/Epoxy Composites in a Simulated Space Environment

1990 ◽  
Vol 112 (3) ◽  
pp. 277-279 ◽  
Author(s):  
G. T. Spirnak ◽  
J. R. Vinson
Keyword(s):  
Room Temperature ◽  
Damping Ratio ◽  
Theoretical Models ◽  
Space Environment ◽  
Effect Of Temperature ◽  
Time Cost ◽  
Material Damping ◽  
Temperature Dependent ◽  
Increasing Temperature ◽  
Free Beam

An experimental method for measuring material damping is described, which employs a free-free beam lightly supported at the nodes. A thermal space environment is simulated by measuring the material damping in air at temperatures ranging from −65°F to 225°F, and then subtracting out the effects of atmospheric damping. This method saves considerable time, cost and experimental difficulties associated with performing the experiments in a vacuum. Graphite/epoxy AS4/3501-6 composite beam specimens were tested. At room temperature, the [0°]12 composites were found to have an average damping ratio of 0.0556 percent. The [90°]12 composites were found to have an average material damping ratio of 0.55 percent. These data agree well with the theoretical models and experimental measurements performed in a vacuum. The material damping ratio is temperature dependent over the range −65°F to 225°F, increasing with increasing temperature. For the [0°]12 composite, the material damping ratio varies from 0.0397 percent at −65°F to 0.083 percent at 225°F. For the [90°]12 composite, the material damping ratio varies from 0.408 percent at −65°F to 0.860 percent at 225°F.

A One Dimensional Mathematical Model for Urodynamics

2007 ◽  
Author(s):  
Ismail B. Celik ◽  
Asaf Varol ◽  
Coskun Bayrak ◽  
Jagannath R. Nanduri
Keyword(s):  
Mathematical Model ◽  
Urinary Incontinence ◽  
3D Visualization ◽  
Current Model ◽  
Theoretical Models ◽  
Parameter Analysis ◽  
Geometrical Parameters ◽  
Urinary Flow ◽  
Detrusor Muscle ◽  
One Dimensional

Millions of people in the world suffer from urinary incontinence and overactive bladder with the major causes for the symptoms being stress, urge, overflow and functional incontinence. For a more effective treatment of these ailments, a detailed understanding of the urinary flow dynamics is required. This challenging task is not easy to achieve due to the complexity of the problem and the lack of tools to study the underlying mechanisms of the urination process. Theoretical models can help find a better solution for the various disorders of the lower urinary tract, including urinary incontinence, through simulating the interaction between various components involved in the continence mechanism. Using a lumped parameter analysis, a one-dimensional, transient mathematical model was built to simulate a complete cycle of filling and voiding of the bladder. Both the voluntary and involuntary contraction of the bladder walls is modeled along with the transient response of both the internal and external sphincters which dynamically control the urination process. The model also includes the effects signals from the bladder outlet (urethral sphincter, pelvic floor muscles and fascia), the muscles involved in evacuation of the urinary bladder (detrusor muscle) as well as the abdominal wall musculature. The necessary geometrical parameters of the urodynamics model were obtained from the 3D visualization data based on the visible human project. Preliminary results show good agreement with the experimental results found in the literature. The current model could be used as a diagnostic tool for detecting incontinence and simulating possible scenarios for the circumstances leading to incontinence.

scholarly journals Influence of Convective and Radiative Cooling on Heat Transfer for a Thin Wire with Temperature-Dependent Thermal Conductivity

2022 ◽  
Vol 17 ◽  
pp. 1-9
Author(s):  
Okey Oseloka Onyejekwe
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Initial Conditions ◽  
Traditional Approach ◽  
Numerical Technique ◽  
System Of Nonlinear Equations ◽  
Thin Wire ◽  
Temperature Dependent ◽  
One Dimensional ◽  
Temperature Dependent Thermal Conductivity

In this study, a numerical prediction of temperature profiles in a thin wire exposed to convective, radiative and temperature-dependent thermal conductivity is carried out using a finite-difference linearization approach. The procedure involves a numerical solution of a one-dimensional nonlinear unsteady heat transfer equation with specified boundary and initial conditions. The resulting system of nonlinear equations is solved with the Newton-Raphson’s technique. However unlike the traditional approach involving an initial discretization in space then in time, a different numerical paradigm involving an Euler scheme temporal discretization is applied followed by a spatial discretization. Appropriate numerical technique involving partial derivatives are devised to handle a squared gradient nonlinear term which plays a key role in the formulation of the Jacobian matrix. Tests on the numerical results obtained herein confirm the validity of the formulation.

scholarly journals Transient Heat Diffusion with Temperature-Dependent Conductivity and Time-Dependent Heat Transfer Coefficient

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Raseelo J. Moitsheki
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Lie Algebras ◽  
Diffusion Problem ◽  
Heat Diffusion ◽  
Temperature Dependent ◽  
One Dimensional ◽  
Surrounding Environment ◽  
Transient Heat Diffusion

Lie point symmetry analysis is performed for an unsteady nonlinear heat diffusion problem modeling thermal energy storage in a medium with a temperature-dependent power law thermal conductivity and subjected to a convective heat transfer to the surrounding environment at the boundary through a variable heat transfer coefficient. Large symmetry groups are admitted even for special choices of the constants appearing in the governing equation. We construct one-dimensional optimal systems for the admitted Lie algebras. Following symmetry reductions, we construct invariant solutions.

Sign in / Sign up

Export Citation Format

Share Document