Non-Newtonian Shear-Thinning Fluid Passing Through a Duct with an Obstacle, Using a Power Law Model

Mohammadi, Moona; Saffarian, Mohammad Reza; Mohammadi, Mohammad-Reza

doi:10.5545/sv-jme.2015.2650

Cited by 3 publications

(1 citation statement)

References 19 publications

(30 reference statements)

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“…This method has been traditionally used to derive empirical equations for calculating the dimensions of hydropower turbines [4,5]. After significant development in numerical techniques and software since the 2000s, this approach has been widely used not only in the hydropower industry but also in a wide range of mechanical problems from water engineering to mechatronic and even non-Newtonian fluids due to its lower cost and faster results in comparison to experimental techniques [6][7][8][9][10]. Computational tools are particularly suitable for investigating flow distribution, vortex formation, and draft tube vibration in hydropower turbines.…”

Section: Introductionmentioning

confidence: 99%

Francis Turbine Draft Tube Troubleshooting during Operational Conditions Using CFD Analysis

Mohammadi,

Hajidavalloo,

Behbahani-Nejad

et al. 2023

Water

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Hydropower plant vibrations due to pressure fluctuations and their troubleshooting methods are some of the most challenging issues in power plant operation and maintenance. This paper targets these fluctuations in a prototype turbine in two geometries: the initially approved design and the as-built design. Due to topographic conditions downstream, these geometries slightly differ in the draft tube height; the potential effect of such a slight geometrical change on the applicability of troubleshooting techniques is investigated. Therefore, the water flow was simulated using the CFD scheme at three operating points based on the SST k–ω turbulence model, while the injection of water/air was examined to decrease the pressure fluctuations in the draft tube, and the outputs were compared with no-injection simulations. The results show that a slight change in draft tube geometry causes the pressure fluctuations to increase 1.2 to 2.8 times after 4 s injecting at different operating points. The modification in the location of the air injection also could not reduce the increase in pressure fluctuations and caused a 3.6-fold increase in pressure fluctuations. Therefore, the results show that despite water/air injection being a common technique in the hydropower industry to reduce pressure fluctuations, it is effective only in the initially approved design geometry. At the same time, it has a reverse effect on the as-built geometry and increases the pressure fluctuations. This research highlights the importance of binding the construction phase with the design and troubleshooting stages and how slight changes in construction can affect operational issues.

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Section: Introductionmentioning

confidence: 99%

Francis Turbine Draft Tube Troubleshooting during Operational Conditions Using CFD Analysis

Mohammadi,

Hajidavalloo,

Behbahani-Nejad

et al. 2023

Water

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A Topical Alginate-Based Wound Gel Fixated with Metal-Based Nanoparticles and Tranexamic Acid as a Hemostatic Wound Healing System

Nqoro,

Adeyemi,

Ubanako

et al. 2023

BioNanoSci.

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Wounds are usually accompanied by complications such as excessive bleeding and bacteria invasion. The design of wound dressings that rapidly stop excessive bleeding and inhibit bacterial invasion, is crucial to promoting accelerated wound healing. To meet the abovementioned requirements in wound dressings, topical gels were prepared from sodium alginate (SA) and carbopol. The wound dressings were loaded with an antifibrinolytic agent, tranexamic acid, and a variety of metal-based nanoparticles. The prepared topical gels displayed significant antibacterial efficacy against Gram-negative bacteria and moderate activity against Gram-positive bacterial strains. These gels exhibited good spreadability and viscosity, signifying suitability for skin application, and ease of application. Moreover, the prepared gels showed good cytocompatibility, promoted cell proliferation, and exhibited > 85% wound closure on day 3 compared to the untreated which showed a 38% wound reduction in vitro. Excellent blood clotting absorbance values were observed for the gels compared to the control, showing that they can promote blood clotting. Features presented by the prepared gels reveal that they are promising wound dressings for treating bleeding and infected wounds.

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Analytical and Computational Modeling of Relaxation Times for Non-Newtonian Fluids

Wang,

Gao,

Wester

et al. 2024

Fluids

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With the availability of efficient and sophisticated finite element analysis (FEA) and computational fluid dynamics (CFD) tools, engineering designs are becoming more software-driven and simulation-based. However, the insights relevant to engineering designs tend to be hidden within massive temporal and spatial data produced with full-fledged three-dimensional simulations. In this paper, we present a preliminary study of the controlled intermittent dispensing of a typical non-Newtonian glue employed in the manufacturing of electric vehicles (EVs). The focus of the study is on the scaling issues derived from different computational and analytical models of interest and importance to the precision control of this non-Newtonian fluid, the lowest dynamic viscosity of which at extremely high shear rates is nearly four million times that of water. More specifically, the abrupt change of the inlet pressure with a constant outlet or ambient pressure and various modeling strategies for transient viscous internal flow with both Newtonian and non-Newtonian fluids are modeled and compared. The analytical and computational results of the developing Newtonian fluid, i.e., water, are derived and computed for validation and verification purposes before the actual applications to the developing non-Newtonian fluid. The concept of a well-established relaxation time before the onset of the steady solution for Newtonian fluids has been validated with both analytical and computational approaches before its expansion and adoption to non-Newtonian fluids with complex rheological behaviors. Other issues attributed to transient operations and precision controls of non-Newtonian fluid delivery involve the pressure pulse and pressure wave propagation within the flexible pipe with compressible or almost incompressible non-Newtonian fluids with a constant pressure at the outlet and a constant mass flow rate or average axial velocity at the inlet, which will be addressed in a separate paper.

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Non-Newtonian Shear-Thinning Fluid Passing Through a Duct with an Obstacle, Using a Power Law Model

Cited by 3 publications

References 19 publications

Francis Turbine Draft Tube Troubleshooting during Operational Conditions Using CFD Analysis

Francis Turbine Draft Tube Troubleshooting during Operational Conditions Using CFD Analysis

A Topical Alginate-Based Wound Gel Fixated with Metal-Based Nanoparticles and Tranexamic Acid as a Hemostatic Wound Healing System

Analytical and Computational Modeling of Relaxation Times for Non-Newtonian Fluids

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