MPZ stability under time-dependent, spatially varying heat loads

1993 ◽  
Vol 3 (1) ◽  
pp. 421-424 ◽  
Author(s):  
E.A. Scholle ◽  
J. Schwartz
Keyword(s):  
Time Dependent ◽  
Spatially Varying ◽  
Heat Loads

Inverse source problem based on two dimensionless dispersion-current functions in 2D evolution transport equations

2016 ◽  
Vol 24 (6) ◽  
Author(s):  
Adel Hamdi ◽  
Imed Mahfoudhi
Keyword(s):  
Velocity Field ◽  
Point Source ◽  
Time Dependent ◽  
Inverse Source Problem ◽  
Two Dimensional ◽  
Reaction Equation ◽  
Advection Dispersion ◽  
Dispersion Tensor ◽  
Spatially Varying ◽  
Dependent Point

AbstractThe paper deals with the nonlinear inverse source problem of identifying an unknown time-dependent point source occurring in a two-dimensional evolution advection-dispersion-reaction equation with spatially varying velocity field and dispersion tensor. The

Some Issues in Ice Mechanics

2015 ◽  
Author(s):  
Ian Jordaan
Keyword(s):  
Damage Mechanics ◽  
Yield Condition ◽  
Threshold Value ◽  
Time Dependent ◽  
Irreversible Processes ◽  
Microstructural Changes ◽  
Weakest Link ◽  
Random Fashion ◽  
Viscoelastic Theory ◽  
Spatially Varying

Ice mechanical behavior is time-dependent, as has been known for many decades. But in many references, the attempt is made to use time-independent plasticity theory. The relevant analytical approach that accounts for time is viscoelastic theory. The need for this approach is made quite essential by study of microstructural changes that occur in ice under high stresses. In no case does there appear to be a clear yield condition, with flow occurring after a certain threshold value. Furthermore, the microstructural changes occurring under stress result in a highly significant enhancement of the creep rates. This results in a spatially varying viscoelastic response that is a function of prior stress history. The ice response is then a function of position resulting in a microstucturally modified layer in the region where compressive stress is applied. This can be deep or highly localized, depending on the loading rate. The most promising approach is that based on damage mechanics combined with viscoelasticity, using the thermodynamics of irreversible processes. Ice is also prone to fracture, especially at high loading rates and under high stresses. This is basic to the notion of scale effect. Fracture processes are also time-dependent in viscoelastic materials, a phenomenon that needs to be explored further. Furthermore, failure often will take place in a random fashion, depending on the distribution of flaws in ice. This indicates strongly that a theory based on “weakest-link” hypotheses and probability theory is appropriate. Finally, some aspects relevant to practical data analysis are discussed. These include measurement uncertainties of Molikpaq data, and geometric approximations of ice features, e.g. ridges as uniform beams.

Stability of Spatially Varying and Time-Dependent Flows

1964 ◽  
Vol 7 (8) ◽  
pp. 1385 ◽  
Author(s):  
D. J. Benney ◽  
S. Rosenblat
Keyword(s):  
Time Dependent ◽  
Spatially Varying

Time-Dependent Conjugate Heat Transfer Characteristics of Self-Sustained Oscillatory Flows in a Grooved Channel

1994 ◽  
Vol 116 (3) ◽  
pp. 499-507 ◽  
Author(s):  
J. S. Nigen ◽  
C. H. Amon
Keyword(s):  
Heat Transport ◽  
Convective Heat ◽  
Heat Generation ◽  
Time Dependent ◽  
Uniform Heat Flux ◽  
Local Skin ◽  
Local Skin Friction ◽  
Multiple Materials ◽  
Conjugate Conduction ◽  
Spatially Varying

Convective heat transport in a grooved channel is numerically investigated using a time-dependent formulation. Conjugate conduction/convection and uniform heat-flux representations for the solid domain are considered. For the conjugate representation, the solid domain is composed of multiple materials and concentrated heat generation. The associated cooling flows include laminar and transitional regimes. Steady and time-dependent contours of the streamfunction and local skin-friction coefficients are presented. Additionally, local distributions of Nusselt number and surface temperature are displayed for both the conjugate and convection-only representations. These results are contrasted over the range of Reynolds numbers explored to demonstrate the significance of including time-dependency and conjugation in the study of convective heat transport. Such considerations are found to be important in the design and analysis of heat exchanger configurations with spatially varying material composition and concentrated heat generation.

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