Three dimensional simulations and stability analysis for convection induced by absorption of radiation

2015 ◽  
Vol 25 (4) ◽  
pp. 810-824 ◽  
Author(s):  
Akil Jassim Harfash
Keyword(s):  
Steady State ◽  
Stability Analysis ◽  
Fluid Layer ◽  
Three Dimensional ◽  
Linear Instability ◽  
Selective Absorption ◽  
Content Type ◽  
Linear Threshold ◽  
Divergence Equation ◽  
Three Dimensional Simulations

Purpose – The purpose of this paper is to investigate a model for convection induced by the selective absorption of radiation in a fluid layer. The concentration based internal heat source is modelled quadratically. Both linear instability and global nonlinear energy stability analyses are tested using three dimensional simulations. The results show that the linear threshold accurately predicts on the onset of instability in the basic steady state. However, the required time to arrive at the steady state increases significantly as the Rayleigh number tends to the linear threshold. Design/methodology/approach – The author introduce the stability analysis of the problem of convection induced by absorption of radiation in fluid layer, then the author select a situations which have very big subcritical region. Then, the author develop a three dimensions simulation for the problem. To do this, first, the author transform the problem to velocity – vorticity formulation, then the author use a second order finite difference schemes. The author use implicit and explicit schemes to enforce the free divergence equation. The size of the Box is evaluated according to the normal modes representation. Moreover, the author adopt the periodic boundary conditions for velocity and temperature in the $x, y$ dimensions. Findings – This paper explores a model for convection induced by the selective absorption of radiation in a fluid layer. The results demonstrate that the linear instability thresholds accurately predict the onset of instability. A three-dimensional numerical approach is adopted. Originality/value – As the author believe, this paper is one of the first studies which deal with study of stability of convection using a three dimensional simulation. When the difference between the linear and nonlinear thresholds is very large, the comparison between these thresholds is very interesting and useful.

Darcy-Forchheimer porous medium effect on rotating hybrid nanofluid on a linear shrinking/stretching sheet

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liaquat Ali Lund ◽  
Zurni Omar ◽  
Ilyas Khan
Keyword(s):  
Porous Medium ◽  
Stability Analysis ◽  
Differential Equations ◽  
Three Dimensional ◽  
Spherical Particles ◽  
Medium Effect ◽  
Hybrid Nanofluid ◽  
Three Dimensional Flow ◽  
Content Type ◽  
Dimensional Flow

Purpose The purpose of this study is to find the multiple branches of the three-dimensional flow of Cu-Al2 O3/water rotating hybrid nanofluid perfusing a porous medium over the stretching/shrinking surface. The extended model of Darcy due to Forchheimer and Brinkman has been considered to make the hybrid nanofluid model over the pores by considering the porosity and permeability effects. Design/methodology/approach The Tiwari and Das model with the thermophysical properties of spherical particles for efficient dynamic viscosity of the nanoparticle is used. The linear similarity transformations are applied to convert the partial differential equations into ordinary differential equations (ODEs). The system of governing ODEs is solved by using the three-stage Lobatto IIIa scheme in MATLAB for evolving parameters. Findings The system of governing ODEs produces dual branches. A unique stable branch is identified with help of stability analysis. The reduced heat transfer rate has been shown to increase with the reduced ϕ2 in both branches. Further, results revealed that the presence of multiple branches depends on the ranges of porosity, suction and stretching/shrinking parameters for the particular value of the rotating parameter. Originality/value Dual branches of the three-dimensional flow of Cu-Al2 O3/water rotating hybrid nanofluid have been found. Therefore, stability analysis of the branches is also conducted to know which branch is appropriate for the practical applications. To the best of the authors’ knowledge, this research is novel and there is no previously published work relevant to the present study.

scholarly journals Stability analysis of the elliptic cylinder wake

2014 ◽  
Vol 763 ◽  
pp. 302-321 ◽  
Author(s):  
Justin S. Leontini ◽  
David Lo Jacono ◽  
Mark C. Thompson
Keyword(s):  
Stability Analysis ◽  
Aspect Ratio ◽  
Three Dimensional ◽  
Elliptic Cylinder ◽  
Cylinder Wake ◽  
Long Wavelength ◽  
Aspect Ratios ◽  
Numerical Stability Analysis ◽  
Spatiotemporal Symmetries ◽  
Three Dimensional Simulations

AbstractThis paper presents the results of numerical stability analysis of the wake of an elliptical cylinder. Aspect ratios where the ellipse is longer in the streamwise direction than in the transverse direction are considered. The focus is on the dependence on the aspect ratio of the ellipse of the various bifurcations to three-dimensional flow from the two-dimensional Kármán vortex street. It is shown that the three modes present in the wake of a circular cylinder (modes A, B and QP) are present in the ellipse wake, and that in general they are all stabilized by increasing the aspect ratio of the ellipse. Two new pertinent modes are found: one long-wavelength mode with similarities to mode A, and a second that is only unstable for aspect ratios greater than approximately 1.75, which has similar spatiotemporal symmetries to mode B but has a distinct spatial structure. Results from fully three-dimensional simulations are also presented confirming the existence and growth of these two new modes in the saturated wakes.

scholarly journals CASE STUDY ON PERFORMANCE MONITORING AND STABILITY ANALYSIS OF BAISHIHU SUSPENSION BRIDGE AND SIDE SLOPE

2022 ◽  
Vol 28 (2) ◽  
pp. 81-92
Author(s):  
Chihcheng Chen ◽  
Ban-Jwu Shih ◽  
Ching-Jiang Jeng
Keyword(s):  
Steady State ◽  
Stability Analysis ◽  
Slope Stability ◽  
Performance Monitoring ◽  
Three Dimensional ◽  
Suspension Bridge ◽  
Steel Beams ◽  
Steel Cable ◽  
Final Steady State ◽  
Steel Cables

The main structure of the Baishihu suspension bridge was connected to the anchor foundations by three main steel cables. The wooden pedestrian deck was fixed to the main steel cables using steel beams and was stabilized by two stabilizing cables. The stabilizing cables and bridge body were joined by 44 steel connecting rods. Therefore, the slope stability at the anchorage foundations of the main steel cables, as well as the performance monitoring and analysis of the main steel cables and stabilizing cables, are critical to the overall performance of the suspension bridge. This paper discusses the performance monitoring and analysis of the steel cable deflection and cable strength for this bridge, as well as the main considerations and results of the stability analysis of the bridge abutments and side slopes of the two banks. Water-level observation wells, inclinometers, and tiltmeters monitoring were used to record reference data for the analysis of the slope stability performance. Additionally, the three-dimensional dynamic analysis program VFIFE was used to analyze the deformation and motion of the bridge. The final steady-state results were used to compare the static design value and monitoring data. The dynamic response before the final steady state was also observed.

A new similarity solution with stability analysis for the three-dimensional boundary layer of hybrid nanofluids

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Najiyah Safwa Khashi'ie ◽  
Norihan M. Arifin ◽  
Ioan Pop ◽  
Roslinda Nazar ◽  
Ezad Hafidz Hafidzuddin
Keyword(s):  
Boundary Layer ◽  
Stability Analysis ◽  
Differential Equations ◽  
Similarity Transformation ◽  
Three Dimensional ◽  
Physical Parameters ◽  
Hybrid Nanofluid ◽  
Content Type ◽  
Boundary Layer Equations ◽  
Dimensional Boundary

Purpose The purpose of this study is to implement a new class of similarity transformation in analyzing the three-dimensional boundary layer flow of hybrid nanofluid. The Cu-Al2O3/water hybrid nanofluid is formulated using the single-phase nanofluid model with modified thermophysical properties. Design/methodology/approach The governing partial differential equations are reduced to the ordinary (similarity) differential equations using the proposed similarity transformation. The resulting equations are programmed in Matlab software through the bvp4c solver to obtain their solutions. The features of the reduced skin frictions and the velocity profiles for different values of the physical parameters are analyzed and discussed. Findings The non-uniqueness of the solutions is observed for certain physical parameters. The dual solutions are perceived for both permeable and impermeable cases and being the main agenda of the work. The execution of stability analysis proves that the first solution is undoubtedly stable than the second solution. An increase in the mass transpiration parameter leads to the uniqueness of the solution. Oppositely, as the injection parameter increase, the two solutions remain. However, no separation point is detected in this problem within the considered parameter values. The present results are decisive to the pair of alumina and copper only. Originality/value The present findings are original and can benefit other researchers particularly in the field of fluid dynamics. This study can provide a different insight of the transformation that is applicable to reduce the complexity of the boundary layer equations.

Three-dimensional stability analysis of robotic machining process

2019 ◽  
Vol 47 (1) ◽  
pp. 82-89
Author(s):  
Feng-Xia He ◽  
Li Dai ◽  
Qisen Chen ◽  
Yu Liu ◽  
Zhong Luo
Keyword(s):  
Stability Analysis ◽  
Dynamic Model ◽  
Stability Criterion ◽  
Dimensional Stability ◽  
Mode Coupling ◽  
Three Dimensional ◽  
Milling Process ◽  
Machining Process ◽  
Content Type ◽  
Robotic Milling

Purpose Since robot’s structural stiffness is usually less than 1 N/µm, mode coupling chatter occurs frequently during robotic milling process, and chatter frequency is close to the natural frequency of the robot itself. Chatter not only affects the surface quality but also damages the robot and reduces the positioning accuracy. Therefore, it is necessary to predict chatter in robotic machining process. Design/methodology/approach A three-dimensional dynamic model for robot’s spatial milling plane is established, and a corresponding stability criterion is obtained. First, the cutting force in milling plane is transformed into the coordinate system of the robot principal stiffness direction based on homogeneous transformation matrix. Then the three-dimensional stability criterion under milling process can be obtained by using system stability analysis. Furthermore, the circle diagram of mode coupling chatter stability is drawn. Each feeding direction’s stability under the two processing forms, referred as spindle vertical milling and spindle horizontal milling, is analyzed. Findings The experimental results verify that the three-dimensional stability criterion can avoid chatter by selecting machining feed direction in stable area. Originality/value This paper established a three-dimensional dynamic model in robot’s spatial milling plane and proposed a three-dimensional stability criterion according to the Routh criterion. The work is also expected to be an efficient tool in the development of robotic milling technology.

“Real” three-dimensional constructive interference in steady-state imaging to discern microneurosurgical anatomy

2003 ◽  
Vol 98 (3) ◽  
pp. 625-630 ◽  
Author(s):  
Yukinari Kakizawa ◽  
Kazuhiro Hongo ◽  
Hisayoshi Takasawa ◽  
Yosuke Miyairi ◽  
Atsushi Sato ◽  
...  
Keyword(s):  
Steady State ◽  
Three Dimensional ◽  
Neurosurgical Procedures ◽  
Constructive Interference ◽  
Operative Field ◽  
Content Type ◽  
Minimal Invasiveness ◽  
Endoscopic View ◽  
Computer Workstation ◽  
The Relationship

✓ Three-dimensional (3D) neuroimages are generally considered useful for neurosurgical practice. Nevertheless, neuroimaging modalities such as 3D digital subtraction angiography and 3D computerized tomography angiography are still insufficient because the resulting images fail to delineate neural structures. Complex neurosurgical procedures are mostly performed in the cerebrospinal fluid (CSF) space of the basal cistern, where vessels and neural structures are present along with the lesion. The magnetic resonance (MR) imaging—derived 3D constructive interference in steady-state (CISS) imaging displays the margin between the CSF and neural structures, vessels, and dura mater in detail, in a two-dimensional fashion. The authors know that volume-rendered 3D CISS images would be more useful for surgery than conventional ones. Although the usefulness of “virtual MR image endoscopy” was reported previously, the endoscopic view is different from the operative field because of the perspective being emphasized. Therefore, to simulate surgical views, the authors made 3D neuroimages from a 3D CISS MR sequence by using an advanced computer workstation. After generating volume images, a cutting method was used in the desired plane to visualize the lesion with reference to a multiplanar reformatted image. The authors call these “real” 3D CISS images, and they are more comparable to the operative field. This newly developed method of producing a real 3D CISS image was used in 30 cases and contributed to the understanding of the relationship between a lesion and surrounding structures before attempting neurosurgical procedures, with minimal invasiveness to the patient.

Electromagnetically driven flow of electrolyte in a thin annular layer: axisymmetric solutions

2017 ◽  
Vol 828 ◽  
pp. 573-600 ◽  
Author(s):  
Sergey A. Suslov ◽  
James Pérez-Barrera ◽  
Sergio Cuevas
Keyword(s):  
Stability Analysis ◽  
Fluid Layer ◽  
Outer Cylinder ◽  
Axisymmetric Flow ◽  
Three Dimensional ◽  
Approximate Solutions ◽  
Annular Layer ◽  
Flow Configurations ◽  
Axisymmetric Solutions

Experimental observations of an azimuthal electrolyte flow driven by Lorentz force in a thin annular fluid layer placed on top of a magnet show that it develops a robust vortical system near the outer cylindrical wall. It appears to be a result of instabilities developing on a background of steady axisymmetric flow. Therefore, the goal of this paper is to establish a scene for a future comprehensive stability analysis of such a flow. We discuss popular depth-averaged and quasi-two-dimensional approximate solutions that take advantage of the thin-layer assumption first, and argue that they cannot lead to the observed flow patterns. Thus, three-dimensional toroidal flows are considered. Their similarities to various other well-studied rotating flow configurations are outlined, but no close match is found. Multiple axisymmetric solutions are detected numerically for the same governing parameters, indicating the possibility of subcritical bifurcations, namely type 1, consisting of a single torus, and type 2, developing a second counter-rotating toroidal flow near the outer cylinder. It is suggested that the transition between these two axisymmetric solutions is likely to be caused by the centrifugal instability, while the shear-type instability of the type 2 solution may be responsible for the observed vortex structures. However, a dedicated stability analysis which is currently underway and will be reported in a separate publication is required to confirm these hypotheses.

Stability analysis for penetrative convection in a fluid layer with throughflow

2016 ◽  
Vol 27 (09) ◽  
pp. 1650101 ◽  
Author(s):  
Akil J. Harfash
Keyword(s):  
Fluid Layer ◽  
Three Dimensional ◽  
Convective Motion ◽  
Linear Instability ◽  
Good Prediction ◽  
Penetrative Convection ◽  
Instability Theory ◽  
Negative Effect ◽  
Regions Of Stability ◽  
Dimensional Simulation

The problem of penetrative convection in fluid layer with vertical throughflow effect is studied by using methods of linear instability theory and unconditional and conditional nonlinear energy theories. Then, the accuracy of the linear instability thresholds are tested using a three-dimensional simulation. For small values of throughflow, the results support the assertion that the linear theory is a good prediction to the onset of convective motion, and thus, regions of stability. However, for large values of throughflow, we found that the actual threshold move from the linear instability threshold with increasing the positive and negative effect of throughflow.

Japanese–French tastes in simulated women’s sportswear t-shirts

2018 ◽  
Vol 30 (5) ◽  
pp. 641-656 ◽  
Author(s):  
Eva Marsac ◽  
KyoungOk Kim ◽  
Masayuki Takatera
Keyword(s):  
Questionnaire Survey ◽  
Design Methodology ◽  
Three Dimensional ◽  
Japanese People ◽  
Content Type ◽  
Sensory Test ◽  
French People ◽  
Three Dimensional Simulations

Purpose The purpose of this paper is to investigate differences in taste in women’s sportswear t-shirts, between Japanese and French people. Design/methodology/approach A questionnaire survey on the impression of the appearance of t-shirts was conducted using three-dimensional simulations that the authors created. A sensory test was carried out for 24 designs (having varying types of sleeves, bodice length and fitting) on 51 examinees (26 Japanese and 25 French) who voluntarily participated. Findings Results show that both Japanese and French people most appreciated very short t-shirts and considered sleeveless and tank top shirts to be the most appropriated for exercise. Participants liked a cool, modern, showy, short, special, elaborate and feminine design. Additionally, Japanese people considered that casual clothes that are suitable for exercise are not suitable for wearing outside the gym, whereas this was not notable for French people. Originality/value The results of the present study will allow the sportswear industry to better target clients.

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