Vertical shear alters chemical front speed in thin-layer flows

2019 ◽  
Vol 874 ◽  
pp. 235-262 ◽  
Author(s):  
Thomas D. Nevins ◽  
Douglas H. Kelley
Keyword(s):  
Thin Layer ◽  
Experimental Studies ◽  
Reaction Diffusion ◽  
Quantitative Agreement ◽  
Vertical Shear ◽  
Front Speed ◽  
Reaction Fronts ◽  
Diffusion Dynamics ◽  
Reactive Mixing ◽  
Front Profile

The mixing of a reactive scalar by a fluid flow can have a significant impact on reaction dynamics and the growth of reacted regions. However, experimental studies of the fluid mechanics of reactive mixing present significant challenges and puzzling results. The observed speed at which reacted regions expand can be separated into a contribution from the underlying flow and a contribution from reaction–diffusion dynamics, which we call the chemical front speed. In prior work (Nevins & Kelley, Chaos, vol. 28 (4), 2018, 043122), we were surprised to observe that the chemical front speed increased where the underlying flow in a thin layer was faster. In this paper, we show that the increase is physical and is caused by smearing of reaction fronts by vertical shear. We show that the increase occurs not only in thin-layer flows with a free surface, but also in Hele-Shaw systems. We draw these conclusions from a series of simulations in which reaction fronts are located according to depth-averaged concentration, as is common in laboratory experiments. Where the front profile is deformed by shear, the apparent front speed changes as well. We compare the simulations to new experimental results and find close quantitative agreement. We also show that changes to the apparent front speed are reduced approximately 80 % by adding a lubrication layer.

scholarly journals The human EDAR 370V/A polymorphism affects tooth root morphology potentially through the modification of a reaction–diffusion system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Keiichi Kataoka ◽  
Hironori Fujita ◽  
Mutsumi Isa ◽  
Shimpei Gotoh ◽  
Akira Arasaki ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Computational Study ◽  
Reaction Diffusion ◽  
Human Migration ◽  
Reaction Diffusion System ◽  
Diffusion System ◽  
Tooth Root ◽  
Computed Tomography Images ◽  
Diffusion Dynamics ◽  
Root Morphogenesis

AbstractMorphological variations in human teeth have long been recognized and, in particular, the spatial and temporal distribution of two patterns of dental features in Asia, i.e., Sinodonty and Sundadonty, have contributed to our understanding of the human migration history. However, the molecular mechanisms underlying such dental variations have not yet been completely elucidated. Recent studies have clarified that a nonsynonymous variant in the ectodysplasin A receptor gene (EDAR370V/A; rs3827760) contributes to crown traits related to Sinodonty. In this study, we examined the association between theEDARpolymorphism and tooth root traits by using computed tomography images and identified that the effects of theEDARvariant on the number and shape of roots differed depending on the tooth type. In addition, to better understand tooth root morphogenesis, a computational analysis for patterns of tooth roots was performed, assuming a reaction–diffusion system. The computational study suggested that the complicated effects of theEDARpolymorphism could be explained when it is considered that EDAR modifies the syntheses of multiple related molecules working in the reaction–diffusion dynamics. In this study, we shed light on the molecular mechanisms of tooth root morphogenesis, which are less understood in comparison to those of tooth crown morphogenesis.

Effect of non-uniform passive advection on A+B->C radial reaction-diffusion fronts 

2021 ◽  
Author(s):  
Alessandro Comolli ◽  
Anne De Wit ◽  
Fabian Brau
Keyword(s):  
Molecular Diffusion ◽  
Early Time ◽  
Reaction Diffusion ◽  
Transport Processes ◽  
Calcium Carbonate Precipitation ◽  
Atmospheric Reactions ◽  
Passive Advection ◽  
Reaction Fronts ◽  
Time Regime ◽  
Long Time

<p>The interplay between chemical and transport processes can give rise to complex reaction fronts dynamics, whose understanding is crucial in a wide variety of environmental, hydrological and biological processes, among others. An important class of reactions is A+B->C processes, where A and B are two initially segregated miscible reactants that produce C upon contact. Depending on the nature of the reactants and on the transport processes that they undergo, this class of reaction describes a broad set of phenomena, including combustion, atmospheric reactions, calcium carbonate precipitation and more. Due to the complexity of the coupled chemical-hydrodynamic systems, theoretical studies generally deal with the particular case of reactants undergoing passive advection and molecular diffusion. A restricted number of different geometries have been studied, including uniform rectilinear [1], 2D radial [2] and 3D spherical [3] fronts. By symmetry considerations, these systems are effectively 1D.</p><p>Here, we consider a 3D axis-symmetric confined system in which a reactant A is injected radially into a sea of B and both species are transported by diffusion and passive non-uniform advection. The advective field <em>v<sub>r</sub>(r,z)</em> describes a radial Poiseuille flow. We find that the front dynamics is defined by three distinct temporal regimes, which we characterize analytically and numerically. These are i) an early-time regime where the amount of mixing is small and the dynamics is transport-dominated, ii) a strongly non-linear transient regime and iii) a long-time regime that exhibits Taylor-like dispersion, for which the system dynamics is similar to the 2D radial case.</p><p>                                  <img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.ff5ab530bdff57321640161/sdaolpUECMynit/12UGE&app=m&a=0&c=360a1556c809484116c55812c8c06624&ct=x&pn=gnp.elif&d=1" alt="" width="299" height="299">                                                     <img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.671a6980bdff51231640161/sdaolpUECMynit/12UGE&app=m&a=0&c=c5a857c3fab835057e3af84001a91d15&ct=x&pn=gnp.elif&d=1" alt="" width="302" height="302"></p><p>                                                   Fig. 1: Concentration profile of the product C in the transient (left) and asymptotic (right) regimes.</p><p> </p><p>References:</p><p>[1] L. Gálfi, Z. Rácz, Phys. Rev. A 38, 3151 (1988);</p><p>[2] F. Brau, G. Schuszter, A. De Wit, Phys. Rev. Lett. 118, 134101 (2017);</p><p>[3] A. Comolli, A. De Wit, F. Brau, Phys. Rev. E, 100 (5), 052213 (2019).</p>

scholarly journals Synchrony and pattern formation of coupled genetic oscillators on a chip of artificial cells

2017 ◽  
Vol 114 (44) ◽  
pp. 11609-11614 ◽  
Author(s):  
Alexandra M. Tayar ◽  
Eyal Karzbrun ◽  
Vincent Noireaux ◽  
Roy H. Bar-Ziv
Keyword(s):  
Pattern Formation ◽  
Large Scale ◽  
Reaction Diffusion ◽  
Biochemical Networks ◽  
Artificial Cells ◽  
Diffusion Dynamics ◽  
Oscillatory Reactions ◽  
Potential Applications ◽  
On Chip ◽  
Genetic Oscillators

Understanding how biochemical networks lead to large-scale nonequilibrium self-organization and pattern formation in life is a major challenge, with important implications for the design of programmable synthetic systems. Here, we assembled cell-free genetic oscillators in a spatially distributed system of on-chip DNA compartments as artificial cells, and measured reaction–diffusion dynamics at the single-cell level up to the multicell scale. Using a cell-free gene network we programmed molecular interactions that control the frequency of oscillations, population variability, and dynamical stability. We observed frequency entrainment, synchronized oscillatory reactions and pattern formation in space, as manifestation of collective behavior. The transition to synchrony occurs as the local coupling between compartments strengthens. Spatiotemporal oscillations are induced either by a concentration gradient of a diffusible signal, or by spontaneous symmetry breaking close to a transition from oscillatory to nonoscillatory dynamics. This work offers design principles for programmable biochemical reactions with potential applications to autonomous sensing, distributed computing, and biomedical diagnostics.

Fourier transform to analyse reaction-diffusion dynamics in a microsystem

Lab on a Chip ◽  
2008 ◽  
Vol 8 (7) ◽  
pp. 1205 ◽  
Author(s):  
André Estévez-Torres ◽  
Thomas Le Saux ◽  
Charlie Gosse ◽  
Annie Lemarchand ◽  
Anne Bourdoncle ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Reaction Diffusion ◽  
Diffusion Dynamics

scholarly journals Influencers identification in complex networks through reaction-diffusion dynamics

2018 ◽  
Vol 98 (6) ◽  
Author(s):  
Flavio Iannelli ◽  
Manuel S. Mariani ◽  
Igor M. Sokolov
Keyword(s):  
Complex Networks ◽  
Reaction Diffusion ◽  
Diffusion Dynamics

Toward Biomolecular Computers Using Reaction-Diffusion Dynamics

2009 ◽  
Vol 1 (3) ◽  
pp. 17-25
Author(s):  
Masahiko Hiratsuka ◽  
Koichi Ito ◽  
Takafumi Aoki ◽  
Tatsuo Higuchi
Keyword(s):  
Reaction Diffusion ◽  
Diffusion Dynamics
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