This paper is concerned with the initial-boundary value problems of scalar transport equations with uncertain transport velocities. It was demonstrated in our earlier works that regularity of the exact solutions in th...This paper is concerned with the initial-boundary value problems of scalar transport equations with uncertain transport velocities. It was demonstrated in our earlier works that regularity of the exact solutions in the random spaces （or the parametric spaces） can be determined by the given data. In turn, these regularity results are crucial to convergence analysis for high order numerical methods. In this work, we will prove the spectral conver- gence of the stochastic Galerkin and collocation methods under some regularity results or assumptions. As our primary goal is to investigate the errors introduced by discretizations in the random space, the errors for solving the corresponding deterministic problems will be neglected.展开更多
In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various resul...In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various results obtained through analyses conducted on velocity fields, different fluxes, and overall transfer coefficients. Due to numerical constraints (resolution of relevant spatial scales), we have restricted the analysis to low Schmidt numbers (S<sub>c</sub><sub></sub>=0.1, S<sub>c</sub></sub>=1, and S<sub>c</sub></sub>=10) and a single roughness Reynolds number (Re<sub>*</sub>=150). The analysis of instantaneous concentration fields from various simulations revealed logarithmic concentration profiles above the canopy. In this zone, the concentration is relatively homogeneous for longer times. The analysis of results also showed that the contribution of molecular diffusion to the total flux depends on the Schmidt number. This contribution is negligible for Schmidt numbers S<sub>c</sub></sub>≥0.1, but nearly balances the turbulent flux for S<sub>c</sub></sub>=0.1. In the canopy, the local Sherwood number, given by the ratio of the total flux (within or above the canopy) to the molecular diffusion flux at the wall, also depends on the Schmidt number and varies significantly between the canopy and the region above. The exchange velocity, a purely hydrodynamic parameter, is independent of the Schmidt number and is on the order of 10% of in the present case. This study also reveals that nutrient absorption by organisms near the wall depends on the Schmidt number. Such absorption is facilitated by lower Schmidt numbers.展开更多
The observation of an electroscalar signal during the eclipse of the Sun by the Moon in 2008 was a starting point for the development and creation of the electroscalar field theory. This observation shows that such ra...The observation of an electroscalar signal during the eclipse of the Sun by the Moon in 2008 was a starting point for the development and creation of the electroscalar field theory. This observation shows that such radiation has a long wavelength, and is longitudinal and extremely penetrating. The properties of the electroscalar and electromagnetic dynamics of a massive charged particle have been studied. An analogy between the linear theory of elasticity and Maxwell electrodynamics is made. The observed spectrum of radiation clarifying peculiar properties. Real sources of electroscalar radiation are determined. In accordance with the principle of least action, the Lagrangian of the electroscalar field and the field force acting on the particle are defined. The spectral expansion of the electroscalar field allowed us to establish that the field is longitudinal and aligned with the wave vector. At the heart of the electroscalar theory, which is compliant with the experimental data, is the four-dimensional scalar potential that describes radial vibrations of the electroscalar field source. The four-vector Maxwell electromagnetic potential and four-scalar potential neither form a single object in the Minkowski space nor interfere and, as a consequence, prove to be independent and unrelated differential relations. Moreover, a strong correlation between the spatial position of the particle and the field components allows and demonstrates a new degree of freedom in the electrodynamics of charged particles.展开更多
基于OpenFOAM中pimpleFoam求解器对具有二级非平衡基元反应(A+B→R)的双平行平面射流中流动-化学反应耦合过程进行数值模拟,研究了不同射流口间距下反应物、生成物浓度标量在流场中心线上的产生、消耗和输运行为。首先将反应性单射流模...基于OpenFOAM中pimpleFoam求解器对具有二级非平衡基元反应(A+B→R)的双平行平面射流中流动-化学反应耦合过程进行数值模拟,研究了不同射流口间距下反应物、生成物浓度标量在流场中心线上的产生、消耗和输运行为。首先将反应性单射流模拟结果与前人实验研究和数值模拟结果进行对比,验证了数值算法的精确性。结果表明:(1)两股射流在准滞止点和混合点的行为直接影响着化学反应。(2)射流相互作用尺度x*可以预测不同射流口间距下反应物和产物的湍流标量统计量。(3)在Da=0.1且Sc=0.71时,反应物和产物由对流过程主导输运。(4)反应物和产物浓度脉动之间的联合概率密度分布(joint probability distribution function,JPDF)呈“心形”,其说明反应物A和反应物B的瞬时浓度在时均值时将有利于化学反应的发生。展开更多
Transfer and transport of a passive scalar as well as flow structures of unbounded flow over a row of 2,3,4 and 5 equispaced identical cylinders at Re=90 and pitch ratios 1.05D≤S≤7D are investigated.Studies are perf...Transfer and transport of a passive scalar as well as flow structures of unbounded flow over a row of 2,3,4 and 5 equispaced identical cylinders at Re=90 and pitch ratios 1.05D≤S≤7D are investigated.Studies are performed through high fidelity simulations using a novel sharp-interface immersed boundary method.Five flow regimes are identified based on the nature of flow in the gap between the first two cylinders:dormant in the gap where fluid in the gap is motionless;symmetric in the gap where fluid in the gap behaves like a cavity flow;alternating in the gap where fluid in the gap is trapped but flaps up and down;wake in the gap where periodic vortices are shed in the gap;and bi-stable flow regime where vortices are shed in the gap for some time and then quasi-periodic twin vortices prevail for other times.A jump in values of hydrodynamic forces,pressure coefficient,Strouhal number,and Sherwood number is observed as pitch ratio increases due to change in flow structure.At high pitch ratio,a convectively unstable two-row vortical train is formed by the second cylinder.Member cylinders immersed in the two-row vortical structures have no effect on flow structure downstream or upstream and portray poor scalar transfer characteristics.The effect of configuration size on flow structures is found not to be as prominent as that of pitch ratio.展开更多
文摘This paper is concerned with the initial-boundary value problems of scalar transport equations with uncertain transport velocities. It was demonstrated in our earlier works that regularity of the exact solutions in the random spaces （or the parametric spaces） can be determined by the given data. In turn, these regularity results are crucial to convergence analysis for high order numerical methods. In this work, we will prove the spectral conver- gence of the stochastic Galerkin and collocation methods under some regularity results or assumptions. As our primary goal is to investigate the errors introduced by discretizations in the random space, the errors for solving the corresponding deterministic problems will be neglected.
文摘In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various results obtained through analyses conducted on velocity fields, different fluxes, and overall transfer coefficients. Due to numerical constraints (resolution of relevant spatial scales), we have restricted the analysis to low Schmidt numbers (S<sub>c</sub><sub></sub>=0.1, S<sub>c</sub></sub>=1, and S<sub>c</sub></sub>=10) and a single roughness Reynolds number (Re<sub>*</sub>=150). The analysis of instantaneous concentration fields from various simulations revealed logarithmic concentration profiles above the canopy. In this zone, the concentration is relatively homogeneous for longer times. The analysis of results also showed that the contribution of molecular diffusion to the total flux depends on the Schmidt number. This contribution is negligible for Schmidt numbers S<sub>c</sub></sub>≥0.1, but nearly balances the turbulent flux for S<sub>c</sub></sub>=0.1. In the canopy, the local Sherwood number, given by the ratio of the total flux (within or above the canopy) to the molecular diffusion flux at the wall, also depends on the Schmidt number and varies significantly between the canopy and the region above. The exchange velocity, a purely hydrodynamic parameter, is independent of the Schmidt number and is on the order of 10% of in the present case. This study also reveals that nutrient absorption by organisms near the wall depends on the Schmidt number. Such absorption is facilitated by lower Schmidt numbers.
文摘The observation of an electroscalar signal during the eclipse of the Sun by the Moon in 2008 was a starting point for the development and creation of the electroscalar field theory. This observation shows that such radiation has a long wavelength, and is longitudinal and extremely penetrating. The properties of the electroscalar and electromagnetic dynamics of a massive charged particle have been studied. An analogy between the linear theory of elasticity and Maxwell electrodynamics is made. The observed spectrum of radiation clarifying peculiar properties. Real sources of electroscalar radiation are determined. In accordance with the principle of least action, the Lagrangian of the electroscalar field and the field force acting on the particle are defined. The spectral expansion of the electroscalar field allowed us to establish that the field is longitudinal and aligned with the wave vector. At the heart of the electroscalar theory, which is compliant with the experimental data, is the four-dimensional scalar potential that describes radial vibrations of the electroscalar field source. The four-vector Maxwell electromagnetic potential and four-scalar potential neither form a single object in the Minkowski space nor interfere and, as a consequence, prove to be independent and unrelated differential relations. Moreover, a strong correlation between the spatial position of the particle and the field components allows and demonstrates a new degree of freedom in the electrodynamics of charged particles.
文摘基于OpenFOAM中pimpleFoam求解器对具有二级非平衡基元反应(A+B→R)的双平行平面射流中流动-化学反应耦合过程进行数值模拟,研究了不同射流口间距下反应物、生成物浓度标量在流场中心线上的产生、消耗和输运行为。首先将反应性单射流模拟结果与前人实验研究和数值模拟结果进行对比,验证了数值算法的精确性。结果表明:(1)两股射流在准滞止点和混合点的行为直接影响着化学反应。(2)射流相互作用尺度x*可以预测不同射流口间距下反应物和产物的湍流标量统计量。(3)在Da=0.1且Sc=0.71时,反应物和产物由对流过程主导输运。(4)反应物和产物浓度脉动之间的联合概率密度分布(joint probability distribution function,JPDF)呈“心形”,其说明反应物A和反应物B的瞬时浓度在时均值时将有利于化学反应的发生。
文摘Transfer and transport of a passive scalar as well as flow structures of unbounded flow over a row of 2,3,4 and 5 equispaced identical cylinders at Re=90 and pitch ratios 1.05D≤S≤7D are investigated.Studies are performed through high fidelity simulations using a novel sharp-interface immersed boundary method.Five flow regimes are identified based on the nature of flow in the gap between the first two cylinders:dormant in the gap where fluid in the gap is motionless;symmetric in the gap where fluid in the gap behaves like a cavity flow;alternating in the gap where fluid in the gap is trapped but flaps up and down;wake in the gap where periodic vortices are shed in the gap;and bi-stable flow regime where vortices are shed in the gap for some time and then quasi-periodic twin vortices prevail for other times.A jump in values of hydrodynamic forces,pressure coefficient,Strouhal number,and Sherwood number is observed as pitch ratio increases due to change in flow structure.At high pitch ratio,a convectively unstable two-row vortical train is formed by the second cylinder.Member cylinders immersed in the two-row vortical structures have no effect on flow structure downstream or upstream and portray poor scalar transfer characteristics.The effect of configuration size on flow structures is found not to be as prominent as that of pitch ratio.
