Liquid Depth Research Articles

Fluid Flow Modeling and Analysis of Low‐ and High‐Gravity Spiral Concentrators: Experimental and Analytical Approaches

AbstractAn experimental evaluation of the flow field on two high‐gravity spiral concentrators is presented along with the analytical solutions. A digital depth gauge was used to measure the liquid level on the spiral troughs. The tracer particle trajectories and the free surface velocity of a spiral were determined with a high‐speed camera. An increase in the flow rate leads to an increase in the liquid depth and free surface velocity along the trough surface. Three full turns of the high gravity spiral concentrator are sufficient for achieving a stabilized flow. High‐gravity spirals show lower flow depths and free surface velocities but steeper depths on the outer trough zone than low‐gravity spirals. Higher flow depths contribute to larger circulation zones, which eventually help in greater separation of heavier minerals from gangue particles.

Effect of drainage device on the transition of dripping and jetting modes

The formation of droplets is a part of many practical engineering problems. Satellite droplets are harmful in the production of traditional Chinese medicines, ink-jet printing, and electronic packaging. It is necessary to investigate the methods to eliminate the satellite droplets. A drainage device was added to the dropper to suppress the formation of satellite droplets. This paper investigated the effects of liquid physical parameters and drainage devices on the fracture length of the neckline and the main-droplet diameter. The effect of the diversion device on the ligament was analyzed using the scaling theories of the Pinch-Off. The effect of the drainage device on the transition of the fluid from the dripping mode to the jetting mode was also investigated. After adding the drainage device, the fracture length of the neckline, the main-droplet diameter, and the number of satellite droplets are significantly reduced. The fracture length of the neckline and the main-droplet diameter decreased with the increase in the length and diameter of the drainage, but the fracture length increased with the increase in liquid depth. With the rise of glycerin mass fraction, the fracture length of the neckline increases, whereas the main-droplet diameter decreases.

Numerical simulation of wave impact and high pressure characteristics due to violent sloshing in a rectangular tank

ABSTRACT Understanding violent sloshing is of practical concern to a wide range of applications as it may compromise safety in a number of engineering applications. The present study investigates violent sloshing in a 2D tank. In particular, the evolution and influence of an air pocket and the impact pressure on tank walls are numerically studied. Since the problem involves multi-phase flows, standard dam-break problem is used for validations. The liquid depth and amplitude of excitation are systematically varied to assess the impact pressures on walls and roof of the tank. Non-linear effects are captured qualitatively and the distribution of impact pressures on the tank walls is examined. The entrainment of an air pocket by a standing wave at the tank roof is delineated. The violent sloshing wave motion causes the formation of air pockets that arise for a range of forcing amplitudes and a variety of liquid depths. Gradual decay in the impact pressure due to the generation of these air pockets is significant on overall sloshing dynamics. The maximum peak pressure predicted on the tank roof is about 10 times the static pressure, which is also about twice the peak pressure obtained on the side wall. Furthermore, the distribution of average impact-pressure profiles on the tank walls and roof is presented for different loading conditions vis-á-vis global impact characteristics of sloshing wave motion.

Hydrogen production from industrial wastes by photo catalysis

This review focuses on our research findings about efficiency of different nano materials synthesized by us for photocatalytic hydrogen production from industrial wastes. Lab-scale photocatalytic reactors were fabricated for hydrogen production from liquid phase alkaline waste streams and gaseous phase hydrogen sulfide. The effects of operating parameters namely pH, flow rate, light intensity, liquid depth, sulfide and sulphite concentration were investigated for for 7 photocatalysts viz., CuGa2-xFexO4/RuO2, Fe2O3-CdS/ZnS, Pd-Cr2O3/CdS, Ce-TiO2, CdS-ZnS/TiO2, CdS/ZnS, Ti-Cr-MCM-48. Among the photocatalysts used, CdS/ZnS nanosized photocatalyts have a much greater surface area and thus give a better hydrogen yield.

Nicotine aerosols diminish airway CFTR function and mucociliary clearance.

Electronic cigarettes (e-cigs) are often promoted as safe alternatives to smoking based on the faulty perception that inhaling nicotine is safe until other harmful chemicals in cigarette smoke are absent. Previously, others and we have reported that, similar to cigarette smoke, e-cig aerosols decrease CFTR-mediated ion transport across airway epithelium. However, it is unclear whether such defective epithelial ion transport by e-cig aerosols occurs in vivo and what the singular contribution of inhaled nicotine is to impairments in mucociliary clearance (MCC), the primary physiologic defense of the airways. Here, we tested the effects of nicotine aerosols from e-cigs in primary human bronchial epithelial (HBE) cells and two animal models, rats and ferrets, known for their increasing physiologic complexity and potential for clinical translation, followed by in vitro and in vivo electrophysiologic assays for CFTR activity and micro-optical coherence tomography (μOCT) image analyses for alterations in airway mucus physiology. Data presented in this report indicate nicotine in e-cig aerosols causes 1) reduced CFTR and epithelial Na+ channel (ENaC)-mediated ion transport, 2) delayed MCC, and 3) diminished airway surface hydration, as determined by periciliary liquid depth analysis. Interestingly, the common e-cig vehicles vegetable glycerin and propylene glycol did not affect CFTR function or MCC in vivo despite their significant adverse effects in vitro. Overall, our studies contribute to an improved understanding of inhaled nicotine effects on lung health among e-cig users and inform pathologic mechanisms involved in altered host defense and increased risk for tobacco-associated lung diseases.

Wave induced vibration control of offshore jacket platform by tuned liquid damper with floating base

The applications of various conventional passive control devices to mitigate wave-induced vibration of offshore structures are remarkable. However, the same is not true for useable liquid storage tanks to utilize as passive vibration control devices for offshore structures due to the low inherent damping of deep tanks. The present study explores the prospect of a usual deep-water storage tank performing as a tuned liquid damper with a floating base (TLD-FB) that overcomes the detuning and liquid level fluctuation effect of a deep tank. The proposed system ensures constant shallow liquid depth over the floating base so that it can act as a usual TLD tuned to the targeted frequency of the structure. To explore the possible modification of the TLD-FB for a large water storage tank, the formulation is further generalized for multiple TLD with floating-based (MTLD-FB). The effectiveness of the TLD-FB and MTLD-FB systems are studied both in the frequency and time domains under irregular waves considering an SDOF system and an MDOF system. The results of the numerical study show that the system is effective in wave-induced vibration mitigation.

Numerical Simulation of White Spot Formation in Vacuum Arc Remelting

Coupling fluid flow, heat transfer, solidification, and particle dissolution behavior, the white spot formation in the vacuum arc remelting process is simulated. The effect of particle initial diameter, dropping position, and dropping height on the remelting behavior is investigated. The results show that the particle from the electrode drops through the arc zone with gravity force and the diameter is reduced in the high‐temperature zone. As the diameter is lower than 5 mm, the particle completely dissolves and the white spot formation can be eliminated. The particle dissolution is less affected by the liquid pool depth, but it is mainly affected by the high‐temperature zone distribution, which is closely related to the electric arc generation. Because of the limited high‐temperature zone near the ingot side surface, the particle from the ingot crown is more difficult to remelt, compared with that from the electrode. Moreover, it is found that the dropping height obviously affects the particle remelting behavior. As the dropping height decreases from 25 to 0, the particle critical diameter that can fully dissolve increases from 4.2 to 6.6 mm.

Kinematic, dynamic and energy characteristics of swirling sloshing waves

The numerical study was made to investigate the evolution of swirling waves during the transient period, including the dynamic, kinematic and energy characteristics of the waves. A rigorous benchmark was made with the experimental measurement to validate the developed numerical model. The viscous effect (Reynolds number effect) of fluid during resonant sloshing was studied and discussed. The beating phenomenon of sloshing waves is described by the relationship between the wave energy and the energy flux transferred from the tank walls. The energy transfer characteristics of swirling waves represent the intensity of sloshing, which can cause significant instability for moving vehicles. The strength of the swirling waves is varied with the excitation angle, excitation frequency and water depth of the tank. The most dangerous excitation angle of a tank during the first beating period is 30°. The beating phenomena of the swirling waves under different water depths exhibit dissimilar behaviours. In the finite depth (d0/L > 0.3), the energy of sloshing waves is still stored inside the tank between the second and third beatings, which will have a serious influence on the stability of the storage containers. The evolutions of swirling waves are very sensitive to physical conditions, including liquid depth, excitation angles, excitation amplitudes and frequencies of external forcing.

Research on Dynamic Liquid Level Detection Technology in Workover Operation

In this paper, an automatic liquid level monitoring device is designed, its working principle and technological process are described, and a workover dynamic liquid level testing scheme is established. In view of the factors affecting the sound velocity in the annular space of the oil jacket, the calculation formula and mathematical model of the sound velocity and the depth pressure temperature density are established. The sound velocity changes caused by the changes in temperature, pressure and the composition of the well gas are accurately corrected. It is confirmed that the modified model provides a method that can not only ensure accuracy but also greatly reduce the calculation amount, greatly simplifying the real-time calculation amount of the system. The obtained liquid level depth is approximate, but it is sufficiently accurate to meet the requirements of the technical indicators of the project.

Mixture formation of OME3−5 and 1-Octanol in comparison with diesel-like Dodecane under ECN Spray A conditions

In order to be able to use the full potential of regenerative fuels, a comprehensive characterization is necessary to identify the differences between conventional fuels and regenerative fuels. In the current work, we compare OME3−5 and 1-Octanol with diesel-like Dodecane in terms of mixture formation under ECN Spray A conditions for single and multi-injection. To determine the mixtures, i.e., the mass distribution and the resulting air-fuel equivalence ratio, Naber and Siebers’ model as well as Musculus and Kattke’s model are used, which are based on experimental data. For this work, the mass flow rates and also the liquid and gaseous penetration depths of the fuel spray are measured. Results show that the mass ratios for the quasi-steady state of a single main injection for all three fuels are nearly the same, whereas the air-fuel equivalence ratios are very different. In addition, multiple injections are used to show that the fuel influences the opening and closing behavior of the injector. In the transient case of multiple injections, completely different mixtures result. In summary, it can be stated that OME3−5 and also 1-Octanol show a clearly different physio-chemical behavior from Dodecane and cannot simply be used as a drop-in fuel. Therefore, a simple exchange is not possible without major adaptations.

Comprehensive refractive manipulation of water waves using electrostriction

The control of wave propagation based on refraction principles offers unparalleled possibilities as shown by the striking example of optics. This approach is unfortunately limited for water waves as it relies mainly on variations of the liquid depth which, while controlling the wave velocity, also trigger nonlinearities and damping. In this article, we show experimentally that electrostriction allows to implement extensive refraction-based control of water waves in a precise and contactless manner. The setup consists of an electrode under high voltage placed above the grounded conductive water. The waves propagating under the electrode can be slowed down up to approximately half their speed compared to free propagation. We characterize the Snell-Descartes laws of refraction and the total internal reflection for the water waves. We implement emblematic refraction-based devices such as electrically tunable focusing lenses, waveguides without obstacles, and beam splitters based on frustrated internal reflection to perform interference experiments.

The invasion law of drilling fluid along bedding fractures of shale

In the process of drilling, the drilling fluid will invade into the bedding plane of shale under the action of pressure difference that will cause hydration collapse and wellbore instability. In order to ensure the wellbore stability during shale oil and gas drilling, it is necessary to clarify the invasion law of drilling fluid along bedding fractures during the drilling process. The immersion experiment method is often used to study the invasion law of drilling fluid, which is quite different from the actual invasion process of drilling fluid underground. In this paper, the depth of drilling fluid invasion into shale under different confining pressures and displacement times is intuitively and accurately determined by the displacement experiment and NMR scanning first. Also, then the mathematical relationships between drilling fluid invasion depth and invasion time, invasion pressure difference, confining pressure, bedding angle, and drilling fluid viscosity were established. The errors between the calculated values of the drilling fluid invasion depth and the experimental values were less than 15%, and the calculation accuracy was high. In addition to the influence of invasion time, formation pressure difference and confining pressure on invasion depth were researched through the method of numerical simulation. The results showed that the liquid invasion depth increased logarithmically with the increase of invasion time and formation pressure difference, but it grew slowly in the later period and tended to be stable; the invasion depth decreased exponentially with the increase of confining pressure, bedding plane angle, and drilling fluid viscosity. The results in the paper provide a basis for the subsequent determination of the collapse pressure and collapse period of bedding shale.

Bank funding constraints and stock liquidity

This paper examines the relationship between bank marginal funding constraints and stock liquidity. Using bank credit default swap (CDS) spreads we show that increased funding constraints weaken bank stock liquidity (as measured by liquidity tightness, depth, and resilience). This effect strengthens during crises periods. Deteriorating bank stock liquidity is in turn priced into excess stock returns. In addition, we find that during liquidity crises, monetary expansion can break the relationship between funding costs and stock liquidity. Heightened monetary policy uncertainty, however, strengthens this relation.

Mechanical energy loss and Rayleigh-Taylor instability in free discharge of vertical sharp-edged orifices

Orifice discharge is a classical hydrodynamic phenomenon. The experiments of liquid free jets through vertical sharp-edged orifices were conducted on the influences of orifice geometry and liquid depth. The flow mechanism indicates that the higher energy loss of thin-walled orifice is caused by the inspired air annulus inside orifice channel which will lead to the Rayleigh-Taylor instability. The theoretical derivation further demonstrated that the consecutive collisions between main stream and surface waves can cause significant energy dissipation. Besides, a kind of transition orifice was found for the first time: the increase of liquid depth can induce a sudden switch from the thick-walled orifice mechanism to the thin-walled one. The presentation in this work on the formation and development of coherent structures, the migration and bursting of vortexes, as well as the interaction between vortexes and free interface, is universal for revealing the essential features of multi-phase flow in form friction.

A numerical analysis of sloshing dynamics of two-layer liquid with a free surface

A numerical study on the two-layer liquid sloshing with a free surface in a rectangular tank under horizontal sinusoidal excitation is investigated in this work. It is observed that the interface displacement is mainly influenced by the lower liquid depth, while the free surface displacement primarily depends on the total liquid depth. Using dimensional analysis of the numerical results, we obtained a fitting curve in the S-model expression, which relates the displacements of both liquids to the forcing amplitude, forcing frequency and liquid depth. Furthermore, distinct from the phenomena for a single-layer liquid, we find that the sum and difference frequencies play significant roles in the power spectral density curves. There are similar power spectral density curve shapes and energy concentration locations with a fixed type of excitation independent of the liquid filling depth and layer depths ratio.

A novel control system approach to enhance the efficiency of solar photo-Fenton microcontaminant removal in continuous flow raceway pond reactors

This work presents a control approach for the continuous flow operation of the solar photo-Fenton process in raceway pond reactors designed for micropollutant (MP) removal from urban wastewater treatment plant secondary effluents. The control system was designed using the mechanistic and semiempirical kinetic model of the photo-Fenton process at acidic pH developed and validated in previous work. Afterwards, a simulation study to demonstrate the viability of the control system was conducted under different operating conditions (hydraulic residence time and liquid depth) for solar irradiance and water temperature variation over the year. Two liquid depths (10 and 20 cm) and two hydraulic residence times (15 and 30 min) were selected as operating conditions to study the system performance for different MP removal control setpoints (70 % and 90 %). For 90 % MP removal setpoint, cost efficiency reductions of up to 21 % were reached, which denotes that the process efficiency is significantly influenced by the control setpoint. This is because highly demanding MP removal setpoints are achieved through high non-linear reagent consumption, resulting in low operating cost efficiencies of the process. On the other hand, cost efficiency improvements from 45 to 50 % were achieved when an 70 % MP removal setpoint was adopted, when comparing the manual operation of the process with the automatic mode. The presented results demonstrate not only the feasibility of implementing an automatic approach for the solar photo-Fenton process, but also the need for an optimised, efficient and controlled operation to upgrade its competitiveness versus conventional technologies.

HOW DO THE MACROECONOMIC DETERMINANTS UNDERPIN THE CAPITAL MARKET DEVELOPMENT IN NORTH MACEDONIA?

The capital market plays a vital role in economic growth since it is an important source of financing the business sector’s investments. Hence, a developed capital market enables efficient financial resource allocation by channeling domestic savings to those that need capital, which in turn leads to increased investment directed towards innovation and supports sustainable growth. The main objective of this research is to examine the impact of macroeconomic determinants on the capital market development in the Republic of North Macedonia. The focus has been put on the investigation of two dependent variables, stock market turnover to GDP ratio and stock market turnover to market capitalization ratio (Turnover Ratio) as parameters resembling the liquidity (depth) of the capital market, and how they depend on the economic growth, macroeconomic stability, trade openness and gross investments to GDP ratio. The empirical study is based on a time-series data analysis based on relevant secondary data sources, based on the utilization of the Johansen Test of Cointegration and the development of a corresponding Vector Error Correction Model (VECM) to estimate the relationship, the impact, the magnitude, and the significance of the determinants that support, and influence the liquidity of the stock market in North Macedonia during the period from 2008:Q1 to 2021:Q4. The analysis shows the existence of a significant long-run relationship between the observed macroeconomic factors and the stock market liquidity. The findings indicate that imports and real interest rates have a negative, yet statistically significant impact on the stock market turnover to GDP ratio. The gross domestic product rate, exports, and inflation rate have all a positive and statistically significant impact on the stock market turnover to GDP ratio. Gross investments also positively affect the stock market turnover to GDP ratio, but not significantly. On the other hand, the analysis shows that gross investments and exports have a positive, yet statistically significant impact on the stock market turnover to market capitalization ratio. The gross domestic product, imports, and inflation rate have all a negative and statistically significant impact, whilst the impact of the interest rates is negative but insignificant.

Microcontaminant removal in solar pilot scale photoreactors with commercial iron nanoparticles obtained from olive mill wastewater

This study assessed removal of microcontaminants (MCs) from natural water (NW) using iron nanoparticles extracted from olive mill wastewater (ZVI-OMW), an agro-industrial waste product, combined with oxidants under natural solar radiation. The specific effects of corrosion, adsorption and solar photolysis, and of H2O2, S2O82-, carbonates and ZVI-OMW concentrations on treatment efficiency were also evaluated. Lab tests demonstrated that the combination of 1 mM S2O82- with NW and 1 mM ZVI-OMW was the best treatment option. Process performance was evaluated under these operating conditions in pilot-scale raceway pond reactors (RPR) at three liquid depths (5, 10 and 15 cm), as well as in a compound parabolic collector (CPC) photo-reactor. The time required to achieve 50% removal of a MC mixture (atrazine, carbendazim, imidacloprid and thiamethoxam, at 100 µg/L each) increased with liquid depth, resulting in 164, 224, and 250 min for 5, 10, and 15 cm, respectively. MC mass removal rate increased with liquid depth, achieving 50% MC removal in the CPC (1 mM ZVI-OMW) in 120 min. Doubling ZVI-OMW concentration was detrimental to process efficiency in both photoreactors due to light obstruction. Partial sedimentation of ZVI-OMW in the RPR suggests that the use of this type of reactor for heterogeneous photocatalysis could present problems for large-size operation.

Numerical Simulation Study of the Effect of Liquid Depth on the Stability of Thermal Marangoni Convection in a Shallow Cavity

The effect of liquid depth on thermal Marangoni convection stability in a shallow cavity was investigated via three-dimensional (3D) numerical simulations. The liquid film in the cavity is silicone oil with a Prandtl number of 6.7. The cavity is subjected to perpendicular temperature gradients. The simulation results show that, for thinner films, a primary instability appears when the flow transits from a steady state to a 3D oscillatory pattern. In thicker films, a secondary instability appears when the flow changes from oscillatory to chaotic. The critical thermal Marangoni numbers (at which transitions occur) of thin films are higher than those of thicker films. The simulation results imply that the uniform steady flow behavior in thinner films can be utilized to a benefit in coating and thin film applications, while the chaotic flow behavior predicted in thicker films can be utilized to obtain better mixing in applications such as lubrication and mixing.

TGA investigation of the volatilisation of fipronil at elevated temperatures

In the present work, thermogravimetric analysis (TGA) was used to study the vaporisation behaviour of fipronil in the temperature range of 150 to 230 °C, i.e., below and above the melting point of the insecticide. The sublimation and evaporation rates were measured using isothermal thermogravimetric analysis. The vapour pressure was estimated assuming that the ideal gas law holds and that the rate of mass loss can be accounted for by the variation of the evaporation rate with liquid depth within the sample crucible and the vapour diffusion coefficient for the evaporating compound into the nitrogen gas. From this, the sublimation enthalpy was determined to be 120 ± 4 kJ⋅mol−1, while the enthalpy of evaporation was 72 ± 5 kJ mol−1. Separate measurements using benzoic acid indicated that the vapour pressure predicted by the thermogravimetric method employed could be accurate to within about 12%.