000164985 001__ 164985
000164985 005__ 20251204150238.0
000164985 0247_ $$2doi$$a10.1007/s10494-017-9888-9
000164985 0248_ $$2sideral$$a104187
000164985 037__ $$aART-2018-104187
000164985 041__ $$aeng
000164985 100__ $$0(orcid)0000-0002-2267-8598$$aDopazo, C.$$uUniversidad de Zaragoza
000164985 245__ $$aStrain, Rotation and Curvature of Non-material Propagating Iso-scalar Surfaces in Homogeneous Turbulence
000164985 260__ $$c2018
000164985 5060_ $$aAccess copy available to the general public$$fUnrestricted
000164985 5203_ $$aThis research aims at gaining some physical insight into the problem of scalar mixing, following the time evolution of propagating iso-surfaces, Y (x, t) = constant, where Y (x, t) stands for any scalar field (e.g., species mass fraction or temperature). First, a rigorous kinematic analysis of non-material line, surface and volume elements, related to propagating iso-scalar surfaces, is presented; this formalism is valid for both constant and variable density flows. Time rates of change of the normal distance and volume between two adjacent iso-surfaces and of area elements, rotation rates of lines and surface elements and an evolution equation for the local mean curvature are obtained. Line and area stretch rates, which encompass additive contributions from the flow and the displacement speed (due to diffusion and reaction), are identified as total strain rates, normal and tangential to the iso-surfaces. Volumetric dilatation rates, addition of line plus area stretch rates, include the mass entrainment rate per unit mass into the non-material volume. Flow and added vorticities, the latter due to gradients of the displacement speed, yield the total vorticity, which provides the real angular velocity of lines and surface elements. A 5123 DNS database for the mixing of inert and reactive scalars in a box of forced statistically stationary and homogeneous turbulence of a constant-density fluid is then examined. A strongly segregated scalar field is prescribed as initial condition. A one-step reaction rate with a characteristic chemical time one order of magnitude greater than the Kolmogorov time micro-scale is used. Data are analyzed at 1.051 large-eddy turnover times after initialization of velocity and scalar fields. Mean negative normal (contractive) and positive tangential (stretching) flow strain rates occur over all mass fractions and scalar-gradient magnitudes. However, means of the total normal strain rate, conditional upon mass fraction, scalar-gradient and mean curvature, are positive everywhere and tend to destroy scalar-gradients for small times. Negative conditioned mean total tangential strain rates (area stretch factor) contract local areas, except for large values of scalar-gradients. Conditional averages of total and added enstrophies are almost identical, which implies a negligible contribution of the flow vorticity to the observed rotation of non-material line and surface elements. The added vorticity is exactly tangential to the iso-surfaces, whereas the flow and total ones are predominantly tangential. Flow sources/sinks of the mean curvature transport equation are much smaller than the added contributions; for this particular DNS database, the local mean curvature development is self-induced by spatial changes of the displacement speed.
000164985 540__ $$9info:eu-repo/semantics/openAccess$$aAll rights reserved$$uhttp://www.europeana.eu/rights/rr-f/
000164985 590__ $$a2.371$$b2018
000164985 591__ $$aTHERMODYNAMICS$$b17 / 60 = 0.283$$c2018$$dQ2$$eT1
000164985 591__ $$aMECHANICS$$b42 / 134 = 0.313$$c2018$$dQ2$$eT1
000164985 592__ $$a0.703$$b2018
000164985 593__ $$aChemical Engineering (miscellaneous)$$c2018$$dQ1
000164985 593__ $$aPhysics and Astronomy (miscellaneous)$$c2018$$dQ1
000164985 593__ $$aPhysical and Theoretical Chemistry$$c2018$$dQ1
000164985 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion
000164985 700__ $$0(orcid)0000-0003-3908-0493$$aMartin, J.$$uUniversidad de Zaragoza
000164985 700__ $$aCifuentes, L.
000164985 700__ $$0(orcid)0000-0002-5821-1666$$aHierro, J.
000164985 7102_ $$15001$$2600$$aUniversidad de Zaragoza$$bDpto. Ciencia Tecnol.Mater.Fl.$$cÁrea Mecánica de Fluidos
000164985 773__ $$g101 (2018), 1-32$$pFlow turbul. combust.$$tFlow, Turbulence and Combustion$$x1386-6184
000164985 8564_ $$s7083817$$uhttps://zaguan.unizar.es/record/164985/files/texto_completo.pdf$$yVersión publicada
000164985 8564_ $$s1462951$$uhttps://zaguan.unizar.es/record/164985/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada
000164985 909CO $$ooai:zaguan.unizar.es:164985$$particulos$$pdriver
000164985 951__ $$a2025-12-04-14:38:45
000164985 980__ $$aARTICLE