Three-dimensional Tube Research Articles

Ruled Strips with Asymptotically Diverging Twisting

We consider the Dirichlet Laplacian in a two-dimensional strip composed of segments translated along a straight line with respect to a rotation angle with velocity diverging at infinity. We show that this model exhibits a "raise of dimension" at infinity leading to an essential spectrum determined by an asymptotic three-dimensional tube of annular cross-section. If the cross-section of the asymptotic tube is a disk, we also prove the existence of discrete eigenvalues below the essential spectrum.

Three-dimensional flows in a hyperelastic vessel under external pressure

We study the collapsible behaviour of a vessel conveying viscous flows subject to external pressure, a scenario that could occur in many physiological applications. The vessel is modelled as a three-dimensional cylindrical tube of nonlinear hyperelastic material. To solve the fully coupled fluid–structure interaction, we have developed a novel approach based on the Arbitrary Lagrangian–Eulerian (ALE) method and the frontal solver. The method of rotating spines is used to enable an automatic mesh adaptation. The numerical code is verified extensively with published results and those obtained using the commercial packages in simpler cases, e.g. ANSYS for the structure with the prescribed flow, and FLUENT for the fluid flow with prescribed structure deformation. We examine three different hyperelastic material models for the tube for the first time in this context and show that at the small strain, all three material models give similar results. However, for the large strain, results differ depending on the material model used. We further study the behaviour of the tube under a mode-3 buckling and reveal its complex flow patterns under various external pressures. To understand these flow patterns, we show how energy dissipation is associated with the boundary layers created at the narrowest collapsed section of the tube, and how the transverse flow forms a virtual sink to feed a strong axial jet. We found that the energy dissipation associated with the recirculation does not coincide with the flow separation zone itself, but overlaps with the streamlines that divide the three recirculation zones. Finally, we examine the bifurcation diagrams for both mode-3 and mode-2 collapses and reveal that multiple solutions exist for a range of the Reynolds number. Our work is a step towards modelling more realistic physiological flows in collapsible arteries and veins.

Hierarchical MoS2-Coated V2O3 composite nanosheet tubes as both the cathode and anode materials for pseudocapacitors

Pseudocapacitors are promising energy storage devices combining the merit of fast charging ability and high energy density. Constructing electrode materials for pseudocapacitors with two-dimensional (2D) materials has become a trending topic. However, it is still a challenge to address the restacking propensity of the 2D materials and to broaden the operational potential window of pseudocapacitors. We herein demonstrate a facile hydrothermal reaction of synthesizing a three-dimensional V2O3 tubes (assembled with ultrathin nanosheets) coated with MoS2 nanosheets and explore their electrochemical properties for pseudocapacitors. The V2O3 tubes prevent the restacking of MoS2 nanosheets and serve as conductive scaffold for fast electron transport. Owing to the multi-valence of both Mo and V, the potential window of composite is able to straddle between negative and positive potentials. Therefore, the V2O3@MoS2 composite electrode exhibits a broad operational potential range between −1.0 V and +1.0 V, and a high reversible capacitance of 655 F g−1 at 20 mV s−1. Moreover, an asymmetric pseudocapacitor with our composite as a positive electrode achieves a high specific capacitance (108.7 F g−1 at 0.5 A g−1), high energy density (31.8 W h kg-1) and excellent cycling stability (no capacitance decay after 35000 cycles).

Local flow boiling heat transfer characteristics in three-dimensional enhanced tubes

Experimental study on local flow boiling heat transfer characteristics in two three-dimensional dimple-grooved tubes (2EHT) and an equivalent smooth tube was performed. All the three test copper tubes have the same inner diameter of 11.07 mm and outer diameter of 12.7 mm. The working fluid was the near-azeotropic mixture, R410A. All test runs were conducted in a 2 m long horizontal tube-in-tube heat exchanger. Constant evaporation temperature was maintained at 10 °C when heat flux ranged from 32.6 kW/m2 to 37 kW/m2. Refrigerant quality varied from inlet 0.1 to outlet 0.9 and mass flux was controlled from 70 kg/(m2 s) to 150 kg/(m2 s). The enhanced surface areas of two 2EHT tubes are 1.02 and 1.03 times of the smooth tube, respectively. The local HTC results of saturate flow boiling were presented and compared with the existing correlations. Wall temperature was measured and critical heat flux effect on the tube-side evaporation was discussed. Local wall temperature results showed that the 2EHT tubes produce a better saturate evaporation at a relatively lower wall superheat. HTC increases with increasing heat flux when heat flux is smaller than CHF and decreases when heat flux is larger than CHF. Based on the local thermal properties, a new flow boiling heat transfer correlation for these 2EHT tubes is derived. The new correlation can predict all the experimental heat transfer coefficients within an error band of ±30% and 96.89% of test data within an error band of ±20%.

Novel online simulation-ready models of conjugate heat transfer in combustion chamber waterwall tubes of supercritical power boilers

This paper presents two models of fluid heating in waterwall tubes of supercritical steam boilers. The models are named 1D/2D and 1D/3D. The models are formulated and discussed in detail with an industrial application example. For the 1D/2D model, a two-dimensional (2D) transient heat conduction equation is solved for the tube wall with the fin domain, while one-dimensional (1D) mass, momentum, and energy equations are solved for the fluid domain. The 1D/3D model considers a three-dimensional tube wall domain (3D) and one-dimensional fluid domain. At the fluid-solid interface, a conjugate heat transfer model is applied. The model is based on convective flux between the fluid and solid domains. Nonlinear governing balance equations of mass, momentum, and energy for fluid are solved using the forward time backward space (FTBS) scheme. The proposed models allow incorporation of the effect of heat flux nonuniformities along the waterwall tube and on its outer circumference. Transient simulations are carried out to determine the temperature histories for both the fluid and the tube wall in the selected cross sections. The computations are performed using the finite volume method formulation. The results obtained from the 1D/2D model are nearly the same as those from the 1D/3D model; however, the computation time is more than five times shorter. Therefore, an efficient 1D/2D model can be used in power unit simulators.

Modelling techniques for fluid–solid coupling dynamics of bundle tubes vibrating and colliding in fluids

ABSTRACTNonlinear vibrations that occur in such bundle structures caused collisions between tubes and cross flows of the surrounding fluid. This paper presents modeling techniques for simulating the FSI dynamics of bundle tubes vibrating and colliding in fluids. A typical configuration of a three-dimensional tube bundles submerged in fluid of a cylindrical container is studied. Coupling conditions of displacement, velocity and forces are considered on the fluid-structure coupling interfaces. Contacts boundary between tubes and topological domain changes of the fluid are also considered on the fluid-structure coupling interface. Modeling techniques and algorithm are then established for flow-induced vibrations of the tubes, and collisions between tubes in fluids. The examples are presented to demonstrate the effectiveness of the proposed techniques. It has confirmed that our code produces the correct physics of the FSI problem, and capable of revealing the complex nonlinear mechanism with solid-solid contacts together with fluid-solid interactions.

Targeted imaging and inhibition of triple-negative breast cancer metastases by a PDGFRβ aptamer.

While the overall mortality for breast cancer has recently declined, management of triple-negative breast cancer (TNBC) is still challenging because of its aggressive clinical behavior and the lack of targeted therapies. Genomic profiling studies highlighted the high level of heterogeneity of this cancer, which comprises different subtypes with unique phenotypes and response to treatment. Platelet-derived growth factor receptor β (PDGFRβ) is an established mesenchymal/stem cell-specific marker in human glioblastoma and, as recently suggested, it may uniquely mark breast cancer cells with stem-like characteristics and/or that have undergone epithelial-mesenchymal transition.Methods: Immunohistochemical analysis for PDGFRβ expression was performed on a human TNBC tissue microarray. Functional assays were conducted on mesenchymal-like TNBC cells to investigate the effect of a previously validated PDGFRβ aptamer on invasive cell growth in three-dimensional culture conditions, migration, invasion and tube formation. The aptamer was labeled with a near-infrared (NIR) dye and its binding specificity to PDGFRβ was assessed both in vitro (confocal microscopy and flow cytometry analyses) and in vivo (fluorescence molecular tomography in mice bearing TNBC xenografts). A mouse model of TNBC lung metastases formation was established and NIR-labeled PDGFRβ aptamer was used to detect lung metastases in mice untreated or intravenously injected with unlabeled aptamer.Results: Here, we present novel data showing that tumor cell expression of PDGFRβ identifies a subgroup of mesenchymal tumors with invasive and stem-like phenotype, and propose a previously unappreciated role for PDGFRβ in driving TNBC cell invasiveness and metastases formation. We show that the PDGFRβ aptamer blocked invasive growth and migration/invasion of mesenchymal TNBC cell lines and prevented TNBC lung metastases formation. Further, upon NIR-labeling, the aptamer specifically bound to TNBC xenografts and detected lung metastases.Conclusions: We propose PDGFRβ as a reliable biomarker of a subgroup of mesenchymal TNBCs with invasive and stem-like phenotype as well as the use of the PDGFRβ aptamer as a high efficacious tool for imaging and suppression of TNBC lung metastases. This study will allow for the significant expansion of the current repertoire of strategies for managing patients with more aggressive TNBC.

Numerical Analysis of Flow Behavior in Vortex Tube for Different Gases

The vortex tube is an energy separation device that separates compressed gas stream into a low and a high temperature stream. Present work reports the flow behavior inside the vortex tube for different commonly used fluids with varied properties like Air, He, N2, CO2 and NH3. Flow behavior investigation for three-dimensional short straight-diverging vortex tube is done with CFD code (ANSYS 16.0). Different turbulent models, standard k-epsilon, Realizable k-epsilon and RNG k-epsilon are tested. Realizable k-epsilon model was then used for analysis. Flow behavior of gases with varied multi-atomic number is analyzed and compared with literature. The effect on temperature for N2 is found to be better, followed by He, CO2, Air and NH3. Energy separation for N2 is 46 % higher than all other gases. Energy separation and flow behavior inside vortex tube is analyzed and compared with literature.

Controlled Recrystallization of Tubular Vinpocetine Crystals with Increased Aqueous Dissolution Rate and In Vivo Bioavailability

Vinpocetine was a BCS II drug, whose clinical applications had suffered from low oral bioavailability because of its inefficient dissolution in the GI tract. As the dissolution rate depended on the surface area of the drug crystals, we herein explored shape-controlled recrystallization via antisolvent process as an excipient-free strategy to improve the bioavailability of VIN. By adjusting the water/ethanol ratio, initial VIN concentration, and temperatures, morphologies of the crystalline products could be finely tuned from three-dimensional cubes and tubes, to two-dimensional frizzled plates, and finally to zero-dimensional microparticle clusters. Morphology analysis and in situ FBRM surveillance of the growing process suggested that a diffusion-limited crystal growth mechanism was responsible for the shape variation of VIN products. Finally, we tested the in vitro dissolution efficiency as well as the in vivo bioavailability of recrystallized VIN crystals. Results manifested that the tubular crystal sh...

The concept of liquid inlet model and its effect on the flooding wave frequency in vertical air-water churn flow

In upward air-water churn flow in a vertical tube, the liquid fed at the inlet is entrained upwards by the gas flow in the core, resulting in a wavy film flow. The present work considers the influence of the modelling of the liquid inlet on the wave frequencies, with the final purpose to understand the causes and effects in an actual flow. The perforated wall liquid inlet section, commonly used in experiments, is modelled in simulations as a simple inlet boundary condition on a short section of a pipe wall. At a given liquid mass flow rate in the experiment, the magnitude of the wall normal velocity component is controlled by the inlet area, which is used as a modelling parameter in the present study. The study shows that the calculated wave frequency is proportional to the imposed wall normal velocity at the liquid inlet. The velocity profile at the perforated wall liquid inlet section was not measured in available experiments and presents a major source of uncertainty in simulations. The parametric study revealed that a suitable value for the magnitude of the wall normal velocity can be determined over a range of flow conditions, leading to good agreement of simulated and measured wave frequencies. This finding suggests, that the wave frequency in actual churn flow is not a property depending only on geometric and flow conditions, but on the liquid inlet flow as well. Simulations were performed in three-dimensional tube section using the multiphase solver interFoam from the open-source code OpenFOAM.

Springback predictions for three-dimensional thick-walled tubes based on the cylindrical helix splines

This article analyzed the forming process of thick-walled three-dimensional tubes under combined bending and twisting loads and performed the springback predictions based on the cylindrical helix splines. The equations to calculate the two kinds of moments consider the hardening effect, and they can be well applied to most materials. The cylindrical helix spline is adopted creatively to approximate the objective tube axis, and the curvature and the torsion of each cylindrical helix segment can represent the bending angle and the twisting angle per unit length of the corresponding tube element, respectively. All the cylindrical helix segments after springback are obtained based on the calculated moments and the final shape of the tube axis is achieved by connecting all of them through an appropriate splicing technology. Then, the whole deviations of the calculated shapes can be obtained. The method proposed is applied on a typical three-dimensional tube forming and it has got good effect.

Influence of buoyancy on turbulent mixed convection of LBE in a uniform cooled inclined tube

The liquid lead-bismuth eutectic (LBE) is a highly promising coolant for new generation nuclear reactors. The experimental loop is usually arranged inclination or vertical for preventing LBE clogging tube at emergency conditions. Because of the high density and low Prandtl number, LBE natural convection due to buoyancy is significant in the inclined tube. In present work, the influence of buoyancy on LBE convective heat transfer is numerically investigated in a three-dimensional circle tube under different inclined angles and length-to-diameter ratios. The turbulent disturbance resulted from buoyancy reinforces convective heat transfer performances of LBE in the inclined tube. The smaller inclined angle and the larger diameter are helpful to enhance convective heat transfer. The dominant factor effect on convective heat transfer is inclined angles rather than length to diameter ratios. Further numerical investigations of LBE heat exchanger with/without buoyancy are performed. The results indicate that LBE heat exchanger of 5° inclined angle can significantly enhance convective heat transfer with the acceptable pressure drop. This structure is also sufficient to ensure LBE flow back to the storage tank when the pump stops. A reasonable and widely applicable selection criterion of inclined angles is necessary to be constructed to guide engineering applications.

A continuum mechanics-based musculo-mechanical model for esophageal transport

In this work, we extend our previous esophageal transport model using an immersed boundary (IB) method with discrete fiber-based structural model, to one using a continuum mechanics-based model that is approximated based on finite elements (IB-FE). To deal with the leakage of flow when the Lagrangian mesh becomes coarser than the fluid mesh, we employ adaptive interaction quadrature points to deal with Lagrangian–Eulerian interaction equations based on a previous work (Griffith and Luo [1]). In particular, we introduce a new anisotropic adaptive interaction quadrature rule. The new rule permits us to vary the interaction quadrature points not only at each time-step and element but also at different orientations per element. This helps to avoid the leakage issue without sacrificing the computational efficiency and accuracy in dealing with the interaction equations. For the material model, we extend our previous fiber-based model to a continuum-based model. We present formulations for general fiber-reinforced material models in the IB-FE framework. The new material model can handle non-linear elasticity and fiber-matrix interactions, and thus permits us to consider more realistic material behavior of biological tissues. To validate our method, we first study a case in which a three-dimensional short tube is dilated. Results on the pressure-displacement relationship and the stress distribution matches very well with those obtained from the implicit FE method. We remark that in our IB-FE case, the three-dimensional tube undergoes a very large deformation and the Lagrangian mesh-size becomes about 6 times of Eulerian mesh-size in the circumferential orientation. To validate the performance of the method in handling fiber-matrix material models, we perform a second study on dilating a long fiber-reinforced tube. Errors are small when we compare numerical solutions with analytical solutions. The technique is then applied to the problem of esophageal transport. We use two fiber-reinforced models for the esophageal tissue: a bi-linear model and an exponential model. We present three cases on esophageal transport that differ in the material model and the muscle fiber architecture. The overall transport features are consistent with those observed from the previous model. We remark that the continuum-based model can handle more realistic and complicated material behavior. This is demonstrated in our third case where a spatially varying fiber architecture is included based on experimental study. We find that this unique muscle fiber architecture could generate a so-called pressure transition zone, which is a luminal pressure pattern that is of clinical interest. This suggests an important role of muscle fiber architecture in esophageal transport.

Investigation of volume fraction of nanoparticles effect and aspect ratio of the twisted tape in the tube

In present study, the heat transfer of laminar and turbulent flow of water/Al2O3 nanofluid in the volume fraction of φ = 0–4% of solid nanoparticles in Reynolds numbers of 500–25,000 have been numerically investigated. The studied geometrics is a three-dimensional tube with the diameter of D = 2 cm and the length of L = 50 cm. In order to increase the heat transfer inside horizontal tube, the twisted tape in different aspect ratios has been used. In this research, the considered geometrics with aspect parameters, such as the twisted ratios (P/W) of 3, 3.5 and 4, the space ratios (C/D) of 0.3, 0.4 and 0.5 and the tape width ratios (W/D) at the range of 0.5–0.9, has been investigated. The results indicate that, in the turbulent flow, the use of solid nanoparticle in higher volume fractions and Reynolds numbers, comparing to the laminar flow, improves heat transfer. The existence of solid nanoparticles in lower twisted ratios (P/W) has great effect on the heat transfer enhancement. In the laminar flow, by increasing the width of twisted tape and the concentration of nanoparticles, heat transfer enhances.

Patterned Polymer Coatings Increase the Efficiency of Dew Harvesting.

Micropatterned polymer surfaces, possessing both topographical and chemical characteristics, were prepared on three-dimensional copper tubes and used to capture atmospheric water. The micropatterns mimic the structure on the back of a desert beetle that condenses water from the air in a very dry environment. The patterned coatings were prepared by the dewetting of thin films of poly-4-vinylpyridine (P4VP) on top of polystyrene films (PS) films, upon solvent annealing, and consist of raised hydrophilic bumps on a hydrophobic background. The size and density distribution of the hydrophilic bumps could be tuned widely by adjusting the initial thickness of the P4VP films: the diameter of the produced bumps and their height could be varied by almost 2 orders of magnitude (1-80 μm and 40-9000 nm, respectively), and their distribution density could be varied by 5 orders of magnitude. Under low subcooling conditions (3 °C), the highest rate of water condensation was measured on the largest (80 μm diameter) hydrophilic bumps and was found to be 57% higher than that on flat hydrophobic films. These subcooling conditions are achieved spontaneously in dew formation, by passive radiative cooling of a surface exposed to the night sky. In effect, the pattern would result in a larger number of dewy nights than a flat hydrophobic surface and therefore increases water capture efficiency. Our approach is suited to fabrication on a large scale, to enable the use of the patterned coatings for water collection with no external input of energy.

Failure analysis of three-dimensional braided composite tubes under torsional load: Experimental study

An experimental study on the effects of braided processes on the torsional strength, torsional modulus and failure modes of the three-dimensional braided composite tubes are presented. Based on the movement of carries, the yarn traces of three-dimensional braided composite tubes are analyzed systematically. Four different three-dimensional braided composite tubes are formed by resin transfer molding, and a number of torsional tests are performed respectively using a special test device. It is found that the torsional strength of three-dimensional five-directional braided composite tubes is higher than others, while the torsional modulus of three-dimensional multi-layer wrapping braided composite tubes is the highest. Furthermore, the damage behaviors of 3D braided composite tubes are significantly influenced by braiding process. One focus is to evaluate the damage mechanism of three-dimensional braided composite tubes by cutting the specimens and using scanning electron microscopy. Under torsional load, three-dimensional five-directional braided composite tubes and three-dimensional surface-core five-directional braided composite tubes are fractured in compression and shear failure, while three-dimensional multi-layer wrapping braided composite tubes and three-dimensional seven-directional braided composite tubes are split open in tensile and shear failure.

Polychlorinated biphenyls target Notch/Dll and VEGF R2 in the mouse placenta and human trophoblast cell lines for their anti-angiogenic effects

The intrauterine environment is particularly vulnerable to environmental exposures. We previously established a mouse model that provided evidence for pregnancy complications and placental anti-angiogenesis in response to Aroclor 1254 (A-1254), a mixture of polychlorinated biphenyls (PCBs). Importantly, these effects were observed in IL-10−/−, but not wild type, mice, suggesting that IL-10 deficiency predisposes to pregnancy disruptive effects of environmental toxicants. However, the mechanisms by which PCBs cause anti-angiogenic effects are unclear. Here, we evaluated PCB-mediated anti-angiogenic effects by diverse but complementary approaches, including HUVEC-mediated trophoblast invasion in nude mice, in vitro three-dimensional capillary tube formation involving HUVEC and/or HTR8 trophoblasts, and aortic ring endothelial cell outgrowth/sprouting. Taken together, our data suggest that PCBs act as potent anti-angiogenic agents. Importantly, we show that treatment of pregnant IL-10−/− mice with A-1254 resulted in placental activation of the Notch/Delta-like ligand (Dll) pathway, a master regulator of cell-cell interaction and vascular patterning. Similar results were obtained with HUVEC and HTR8 trophoblasts. Rescue of A-1254-induced disruption of HUVEC-based tube formation by γ-secretase inhibitor L1790 confirmed the critical role of the Notch/Dll pathway. Our data suggest that PCBs impart pregnancy disruptive functions by activating the Notch/Dll pathway and by inducing anti-angiogenic effects at the maternal-fetal interface.

A Three-Dimensional Lymphatic Endothelial Cell Tube Formation Assay to Identify Novel Kinases Involved in Lymphatic Vessel Remodeling.

The lymphatic system is a series of vessels that transport cells and excess fluid from tissues to the blood vascular system. Normally quiescent, the lymphatics can grow or remodel in response to developmental, immunological, or cells pathological stimuli. Lymphatic vessels comprise lymphatic endothelial cells (LECs) that can respond to external growth factors by undergoing proliferation, migration, adhesion, and tube and lumen formation into new vessel structures, a process known as lymphangiogenesis. To understand the key gene and signaling pathways necessary for lymphangiogenesis and lymphatic vessel remodeling, we have developed a three-dimensional LEC tube formation assay to explore the role of kinase signaling in these processes. The collagen-overlay-based assay was used with primary human adult dermal LECs to investigate a library of 60 tyrosine kinase (TK) and TK-like genes by siRNA knockdown. Nine candidate genes were identified and characterized for their ability to modify key parameters of lymphatic tube formation, including tube length, area, thickness, branching, and number of blind-ended sacs. Four genes-ZAP70, IRAK4, RIPK1, and RIPK2-were identified as high-confidence hits after tertiary deconvolution screens and demonstrate the utility of the assay to define LEC genes critical for the formation of tube structures. This assay facilitates the identification of potential molecular targets for novel drugs designed to modulate the remodeling of lymphatics that is important for the metastatic spread of cancer and other pathologies.

3D Printing Process for Hydro Gel with the Three-dimensional Micro Tubes to Mimic Vascular Network

3D Printing Process for Hydro Gel with the Three-dimensional Micro Tubes to Mimic Vascular Network

Computation of Micro-Strains in Cold Formed Steels- FEA Approach

This paper describes the computations of micro-strains at inner corner of cold formed rectangular hollow sections (CFRHS) made up of structural steels using finite element analysis. In order to obtain the micro-strains, distortion test is simulated by modeling two-dimensional structural steel tubes in ANSYS software. Two dimensional linear static analyses are performed by defining elastic properties of steel. These simulations were performed for tubes with outer radius to thickness (<i>r_o/t</i>) ratios of 3. In real distortion tests, the direction of force at outer corner of the tube may vary in terms of angle. Therefore, this fact is taken into account while performing simulations. One more aspect is taken into consideration which is related to strain gauge placement during distortion testing. This problem is analyzed by modeling three-dimensional structural tubes and performing linear static analyses to investigate the variations in strains at inner bent section of the tube with different strain gauge locations.