Investigation of pulp flow helicity in rotating and non-rotating grooves

2021 ◽  
pp. 095440892110274
Author(s):  
Nima F Jouybari ◽  
Birgitta Engberg ◽  
Johan Persson ◽  
Jan-Erik Berg
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Turnover Rate ◽  
Working Fluid ◽  
Flow Structures ◽  
Experimental Measurements ◽  
Fiber Concentration ◽  
Eucalyptus Pulp ◽  
Helicity Distribution ◽  
Viscosity Correlation

Numerical simulation of pulp flow in rotating and non-rotating grooves is carried out to investigate the effect of pulp rheological properties and groove geometry on the rotational motion of the pulp flow. The eucalyptus pulp suspension is considered as a working fluid in the present study whose apparent viscosity correlation is available from the experimental measurements reported in the literature. The simulations are carried out with OpenFoam for different values of pulp material, fiber concentrations, and groove cross-section. Helicity is introduced to measure the turnover rate of pulp flow in the groove due to the importance of such motion on the final properties of the pulp flow. A measurement of helicity magnitude and its distribution along the groove revealed that a change in the pulp material would significantly affect the flow structures within the groove. Further investigation on the effects of fiber concentration, c, showed that this parameter does not have a significant effect on the averaged helicity magnitude for c = 2.0 and 2.5, whereas the helicity distribution over the groove cross-section changes clearly for c = 1.5. The results showed that the helicity level is negligible for almost half of the cavity cross-section in the non-rotating groove simulations, which can be considered as a shortcoming of the original geometry of the groove. Therefore, a smaller cross-section for the groove is considered through which an enhancement in the helicity magnitude is observed.

Numerical Simulation of Vertical Forced Plume in a Crossflow of Stably Stratified Fluid

1995 ◽  
Vol 117 (4) ◽  
pp. 696-705 ◽  
Author(s):  
Robert R. Hwang ◽  
T. P. Chiang
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Cross Section ◽  
Three Dimensional ◽  
Experimental Measurements ◽  
Secondary Vortex ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Vortex Pairs ◽  
Plume Flows

In this study, an investigation using a three-dimensional numerical model, which treats conservation of mass, momentum, and salinity simultaneously, was carried out to study the character of a vertical forced plume in a uniform cross-stream of stably linear stratified environment. A k-ε turbulence model was used to simulate the turbulent phenomena and close the solving problem. The performance of the three-dimensional model is evaluated by comparison of the numerical results with some available experimental measurements. Results indicate that the numerical computation simulates satisfactorily the plume behavior in a stratified crossflow. The secondary vortex pairs in the cross section induced by the primary one change as the plume flows downstream. This denotes the transformation of entrainment mechanism in stratified crossflow.

Transport From a Volatile Meniscus in a Microtube

2006 ◽  
Author(s):  
Hao Wang ◽  
Jayathi Y. Murthy ◽  
Suresh V. Garimella
Keyword(s):  
Temperature Gradient ◽  
Cross Section ◽  
Temperature Gradients ◽  
Flow Structures ◽  
Experimental Measurements ◽  
Marangoni Flow ◽  
Asymmetric Flow ◽  
Large Vortex ◽  
Volatile Liquid ◽  
Small Vortex

Transport at the meniscus of a volatile liquid evaporating inside a microtube is numerically investigated. Evaporation at the meniscus is coupled with the vapor diffusion into the ambient. The evaporation is found to be stronger at the corner of the meniscus than at its center, which creates a temperature gradient resulting in thermocapillary or Marangoni flow along the meniscus. The existence of either gravity or mild imposed temperature gradients results in asymmetric flow structures. For a meniscus in a horizontal microtube, a large vortex near the meniscus covers much of the diametric cross-section of the tube, with a small vortex present above. The simulations are consistent with experimental measurements.

Numerical Simulation of the Effects of Preheating on Electron Beam Additive Manufactured Ti-6Al-4V Build Plate

2016 ◽  
Vol 879 ◽  
pp. 274-278 ◽  
Author(s):  
Jun Cao ◽  
Philip Nash
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Finite Element ◽  
Electron Beam ◽  
Cross Section ◽  
Element Model ◽  
Normal Direction ◽  
Thermal Residual Stresses ◽  
Longitudinal Residual Stress ◽  
Middle Cross Section

In an earlier study, a 3-D thermomechanical coupled finite element model was built and experimentally validated to investigate the evolution of the thermal residual stresses and distortions in electron beam additive manufactured Ti-6Al-4V build plates. In this study, an investigation using this robust and accurate model was focused on an efficient preheating method, in which the electron beam quickly scanned across the substrate to preheat the build plate prior to the deposition. Various preheat times, beam powers, scan rates, scanning paths and cooling times (between the end of current preheat scan/deposition layer and the beginning of the next preheat scan/deposition layer) were examined, and the maximum distortion along the centerline of the substrate and the maximum longitudinal residual stress along the normal direction on the middle cross-section of the build plate were quantitatively compared. The results show that increasing preheat times and beam powers could effectively reduce both distortion and residual stress for multiple layers/passes components.

Optimal Solutions for Nonhomogeneous Multiply-Connected Torsional Sections

1989 ◽  
Vol 111 (1) ◽  
pp. 87-93 ◽  
Author(s):  
A. Mioduchowski ◽  
M. G. Faulkner ◽  
B. Kim
Keyword(s):  
Numerical Simulation ◽  
Boundary Value Problem ◽  
Cross Section ◽  
Boundary Value ◽  
Optimization Procedure ◽  
Second Order ◽  
External Boundary ◽  
Optimal Solutions ◽  
Torsion Problem ◽  
Multiply Connected

Optimization of a second-order multiply-connected inhomogeneous boundary-value problem was considered in terms of elastic torsion. External boundary and material proportions are the applied constraints in finding optimal internal configurations of the cross section. The optimization procedure is based on the numerical simulation of the membrane analogy and the results obtained indicate that the procedure is usable as an engineering tool. Optimal solutions are obtained for some representative cases of the torsion problem and they are presented in the form of tables and figures.

scholarly journals Flow topologies in primary atomization of liquid jets: a direct numerical simulation analysis

2018 ◽  
Vol 859 ◽  
pp. 819-838 ◽  
Author(s):  
Josef Hasslberger ◽  
Sebastian Ketterl ◽  
Markus Klein ◽  
Nilanjan Chakraborty
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Direct Numerical Simulation ◽  
Incompressible Flows ◽  
Flow Structures ◽  
Liquid Jets ◽  
Small Scale ◽  
Flow Topology ◽  
Local Flow ◽  
Turbulent Length Scale

The local flow topology analysis of the primary atomization of liquid jets has been conducted using the invariants of the velocity-gradient tensor. All possible small-scale flow structures are categorized into two focal and two nodal topologies for incompressible flows in both liquid and gaseous phases. The underlying direct numerical simulation database was generated by the one-fluid formulation of the two-phase flow governing equations including a high-fidelity volume-of-fluid method for accurate interface propagation. The ratio of liquid-to-gas fluid properties corresponds to a diesel jet exhausting into air. Variation of the inflow-based Reynolds number as well as Weber number showed that both these non-dimensional numbers play a pivotal role in determining the nature of the jet break-up, but the flow topology behaviour appears to be dominated by the Reynolds number. Furthermore, the flow dynamics in the gaseous phase is generally less homogeneous than in the liquid phase because some flow regions resemble a laminar-to-turbulent transition state rather than fully developed turbulence. Two theoretical models are proposed to estimate the topology volume fractions and to describe the size distribution of the flow structures, respectively. In the latter case, a simple power law seems to be a reasonable approximation of the measured topology spectrum. According to that observation, only the integral turbulent length scale would be required as an input for the a priori prediction of the topology size spectrum.

scholarly journals Mathematical modeling and numerical simulation of heat dissipation in led bulbs

2020 ◽  
Vol 24 (3 Part A) ◽  
pp. 1877-1884 ◽  
Author(s):  
Diego Alarcón ◽  
Eduardo. Balvís ◽  
Ricardo Bendaña ◽  
Alberto Conejero ◽  
de Fernández ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Numerical Simulation ◽  
Numerical Simulations ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Thermal Contact ◽  
Heat Sinks ◽  
Experimental Measurements ◽  
Heating And Cooling ◽  
The Common

We present a detailed study of heating and cooling processes in LED luminaires with passive heat sinks. Our analysis is supported by numerical simulations as well as experimental measurements, carried on commercial systems used for outdoor lighting. We have focused our analysis on the common case of a single LED source in thermal contact with an aluminum passive heat sink, obtaining an excellent agreement with experimental measurements and the numerical simulations performed. Our results can be easily expanded, without loss of generality, to similar systems.

Numerical and Experimental Evaluation of Turbulent Flow in Volute

2003 ◽  
Author(s):  
Akitomo Igarashi ◽  
Kazuyuki Toda ◽  
Makoto Yamamoto ◽  
Toshimichi Sakai
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Three Dimensional ◽  
Experimental Result ◽  
Centrifugal Fan ◽  
Flow Conditions ◽  
Flow Angle ◽  
Fan Performance ◽  
Centrifugal Fans ◽  
Good Agreement

The performance of centrifugal fans is considerably influenced by the design of tongue at the re-circulation port. The flow in the volute of a centrifugal fan was studied both experimentally and numerically. In this experiment, flow angle, pressure and velocity profiles were measured at a large number of locations in the volute. The flow field in the volute passage was analyzed using Computational Fluid Dynamics. The flow was assumed to be three dimensional, turbulent and steady. The numerical simulation produced qualitatively good agreement with the experimental result. The results from experiment and numerical simulation indicated that the adoption of a re-circulating flow port improved fan performance for all flow conditions. In addition, the existence of strong secondary flow was apparent at the cross-section of the volute passage.

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