Homogeneous Fluid Research Articles

Detection of islands and droplets on smectic films using machine learning

Machine learning techniques have been developed to identify inclusions on the surface of freely suspended smectic liquid crystal films imaged by reflected light microscopy. The experimental images are preprocessed using Canny edge detection and then passed to a radial kernel support vector machine (SVM) trained to recognize circular islands and droplets. The SVM is able to identify these objects of interest with an accuracy that far exceeds that of conventional tracking software, especially when the background image is non-uniform or when the target features are in close proximity to one another. This method could be applied to tracking objects in a variety of visually inhomogeneous fluid environments, in order to study growth dynamics, the development of spatial order, and hydrodynamic behavior.

Volume scattering of sound signals in gassy bottom and estimation of bubbles concentration in Lake Kinneret

In the paper, results of experiments in shallow Lake Kinneret (Israel) and the corresponding data processing are presented. Wideband LFM sound signals (300 Hz–3.50 kHz and 300 Hz–15 kHz) were radiated by the source mounted directly on vertical line array (VLA) of the length 20 m placed at several locations with different water depths (from 20 to 35 m). Received sound field timeseries constitutes a sequence of pulse arrivals comprised of specular reflections from interfaces followed by reverberation codas caused by non-specular scattering from the interface roughness and volume inhomogeneity. Properties of received signals are analyzed assuming that the sediment can be modeled as a thin layer containing bubbles over a homogeneous fluid half-space. Using a set of hydrophones of VLA allowed isolation of the volume scattering component, estimating frequency-angle dependences of scattered field, and hypothesizing some properties of the gassy sediment, such as concentration of bubbles and their effective size. [Work was supported by BSF grant 2018150.].

Ore fluid characteristics and depositional processes of the hydrothermal gold mineralisation at Damang, Southwestern Ghana

Gold mineralisation at Damang in the southwestern part of Ghana occurs in two types of geological settings: (1) as paleoplacer in the Banket Series conglomerates of the Tarkwaian system and (2) in hydrothermal sheeted quartz vein system that crosscuts all the Tarkwaian lithologies including the palaeoplacer units. This paper focused on the second type because not much research has be conducted on the fluid inclusion and stable isotope characteristics of the Damang deposit to reveal the nature of the hydrothermal ore-forming associated the quartz veins and gold deposition. Microthermometry measurements of fluid inclusions in mineralised quartz veins indicated two sets of temperature-salinity variations: a relatively low temperature (142–292 °C) and moderate salinity aqueous fluids that range from 2.4 to 8.9 wt% NaCl equivalent, and a high temperature (210–393.6 °C) with low salinity aqueous-carbonic fluids with the salinity ranging from 1.0 to 2.6 wt% NaCl equivalent. These fluids are inferred to have unmixed from a homogeneous fluid with an average salinity of 3.85 ± 2.42 wt % NaCl equivalent. Laser Raman spectroscopic data on the fluid inclusions confirmed an aqueous-carbonic (H2O–CO2–NaCl) composition of the fluids with minor amounts of H2S, CH4 and SO2 as volatile species. The temperature of gold precipitation based on overlapped temperatures of chlorite, fluid inclusions and stable isotope geothermometers, indicated a mean temperature of 324.7 ± 20 °C and corresponding pressures from 1.1 to 3.5 kbar. The calculated oxygen isotopic composition of the ore fluids, δ18Ofluid using the estimated mineralisation temperature indicated average values of 9.3 ± 1.2‰. This isotopic range and the low salinity of the fluids (<10 wt % NaCl equiv.) are suggestive of metamorphic origin, which may be attributed to devolatisation reactions in the underlying Birimian greenstones. This is consistent with orogenic lode gold mineralisation in many Precambrian greenstone belts worldwide. The close association of gold with sulphides is consistent with gold transport as bisulphide complexes. A combination of factors including sulphidation and phase separation, concomitant with temperature decrease are inferred to be the principal factors that controlled the hydrothermal gold precipitation at Damang.

Synthesis of Hollow Fe3O4 Magnetic Nanospheres and Their Application in Magnetorheological Fluids

Magnetorheological fluid (MRF) is a rapidly developing emerging intelligent material with excellent properties, featuring fast response time, reversible rheological properties, controllable mechanical properties and a wide range of operating temperature. It is widely used in engineering fields such as shock absorbers, clutches, sensors and dampers. In this paper, hollow structured Fe3O4 magnetic nanospheres were synthesized by using a facile one-step hydrothermal method, and then their comprehensive properties such as morphology, structure and magnetic properties were thoroughly characterized by using analytical techniques such as scanning electron microscope, transmission electron microscope, X-ray diffraction and superconducting quantum magnetic interferometry, and then, a homogeneous magnetorheological fluid was prepared by using the prepared hollow Fe3O4 magnetic nanospheres as the dispersed phase, and finally the rheological properties and sedimentary stability of magnetorheological fluid were tested by rotational rheometer and direct observation method respectively.

A tale of elemental accumulation and recycling in the metamorphosed Keketale VMS-type Pb-Zn deposit, Altai Mountains

The elemental accumulation and recycling in the metamorphosed Keketale VMS-type Pb-Zn deposit of the Altai Mountains are presented in this study. Based on detailed fieldwork and microscopic observation, the formation of the deposit involved syngenetic massive sulfide mineralization and epigenetic superimposed mineralization. Different generations of iron sulfides (i.e., pyrite and pyrrhotite) with contrasting textural, elemental, and sulfur isotopic features were generated in primary mineralization (including hydrothermal iron sulfides, colloform pyrite) and secondary modification (including annealed iron sulfides, oriented iron sulfides, and vein-pyrite). It is revealed that the spatial variation in textures and elements of hydrothermal iron sulfides depends on the inhomogeneous fluid compositions and varied environment in VMS hydrothermal system. Both leached sulfur from the footwall volcanic rocks and reduced sulfur by the TSR process are regarded as important sulfur sources. Furthermore, large sulfur isotopic fractionation and negative δ34S values were mainly caused by varied oxygen fugacity, and to a lesser extent, temperature fluctuation. The epigenetic polymetallic veins that contain sulfides and sulfosalts (e.g., jordanite-geocronite, bournonite-seligmannite, boulangerite) were considered as the products of metamorphic fluid scavenged the metal-rich strata. All things considered, it is indicated that two episodes of fluid with distinct origins were essential for the formation of the deposit. The predominant evolved seawater along with subordinate magmatic fluid mobilized metals from volcanic rocks and precipitated massive sulfides near the seafloor are vital for primary mineralization. The metamorphic fluid remobilized metals (i.e., FMEs: fluid mobile elements, e.g., Pb, As, Sb) from neighboring volcanic and pyroclastic rocks and destabilized them within the fractured zone are responsible for secondary mineralization, which enhances the economic value of the deposit. Accordingly, metal-rich Devonian strata had been successively swept by different origins of fluid, leading to progressively elemental enrichment and the formation of a large deposit. Furthermore, the current study enlightens that FME-bearing veins with economic benefits can be discovered near the metamorphosed VMS deposits.

Conformally Schwarzschild cosmological black holes

We thoroughly investigate conformally Schwarzschild spacetimes in different coordinate systems to seek for physically reasonable models of a cosmological black hole. We assume that a conformal factor depends only on the time coordinate and that the spacetime is asymptotically flat Friedmann–Lemaître–Robertson–Walker Universe filled by a perfect fluid obeying a linear equation state p = wρ with w > −1/3. In this class of spacetimes, the McClure–Dyer spacetime, constructed in terms of the isotropic coordinates, and the Thakurta spacetime, constructed in terms of the standard Schwarzschild coordinates, are identical and do not describe a cosmological black hole. In contrast, the Sultana–Dyer and Culetu classes of spacetimes, constructed in terms of the Kerr–Schild and Painlevé–Gullstrand coordinates, respectively, describe a cosmological black hole. In the Sultana–Dyer case, the corresponding matter field in general relativity can be interpreted as a combination of a homogeneous perfect fluid and an inhomogeneous null fluid, which is valid everywhere in the spacetime unlike Sultana and Dyer’s interpretation. In the Culetu case, the matter field can be interpreted as a combination of a homogeneous perfect fluid and an inhomogeneous anisotropic fluid. However, in both cases, the total energy–momentum tensor violates all the standard energy conditions at a finite value of the radial coordinate in late times. As a consequence, the Sultana–Dyer and Culetu black holes for −1/3 < w ⩽ 1 cannot describe the evolution of a primordial black hole after its horizon entry.

Two-dimensional hydrofoil hydrodynamic performance and waveform evolution studies in density stratification and homogeneous fluid

This paper presents a numerical simulation study of the hydrodynamic coefficients, surrounding flow and generated internal waves of the NACA0012 hydrofoil in two-dimensional unsteady incompressible viscous stratified and uniform flows using computational fluid dynamics (CFD) methods. The Reynolds-averaged Navier-Stokes equations are discretized using the finite volume method (FVM) and combined with the volume of fluid (VOF) method to capture the interface between different phases. The k-ω SST turbulence model is used to predict the turbulent flow around the hydrofoil under different conditions. In order to validate the numerical methods, the simulation values are compared with the experimental results in this paper. The hydrodynamic coefficients and generated flow fields of hydrofoils in a stratified flow environment, i.e. water velocities, angles of attack, freshwater layer thicknesses, density differences and submergence depths are investigated. The surrounding flow fields and hydrodynamic characteristics of the hydrofoil in stratified flow are revealed by comparing the force coefficients and flow fields in homogeneous flow environment. The results show that compared to uniform flow, the hydrofoil can have a maximum loss of lift coefficient of 10.29% and a maximum reduction in drag coefficient of 49.1% in a stratified flow environment. Choosing the right variable can significantly improve the lift-to-drag ratio.

Solution of an acoustic transmission inverse problem by extended inversion

Study of a simple single-trace transmission example shows how an extended source formulation of full-waveform inversion can produce an optimization problem without spurious local minima (‘cycle skipping’), hence efficiently solvable via Newton-like local optimization methods. The data consist of a single trace extracted from a causal pressure field, propagating in a homogeneous fluid according to linear acoustics, and recorded at a given distance from a transient point energy source. The source intensity (‘wavelet’) is presumed quasi-impulsive, with zero energy for time lags greater than a specified maximum lag. The inverse problem is: from the recorded trace, recover both the sound velocity or slowness and source wavelet with specified support, so that the data is fit with prescribed RMS relative error. The least-squares objective function has multiple large residual minimizers. The extended inverse problem permits source energy to spread in time, and replaces the maximum lag constraint by a weighted quadratic penalty. A companion paper shows that for proper choice of weight operator, any stationary point of the extended objective produces a good approximation of the global minimizer of the least squares objective, with slowness error bounded by a multiple of the maximum lag and the assumed noise level. This paper summarizes the theory developed in the companion paper and presents numerical experiments demonstrating the accuracy of the predictions in concrete instances. We also show how to dynamically adjust the penalty scale during iterative optimization to improve the accuracy of the slowness estimate.

Unexpected diversity found within benthic microbial mats at hydrothermal springs in Crater Lake, Oregon.

Crater Lake, Oregon is an oligotrophic freshwater caldera lake fed by thermally and chemically enriched hydrothermal springs. These vents distinguish Crater Lake from other freshwater systems and provide a unique ecosystem for study. This study examines the community structure of benthic microbial mats occurring with Crater Lake hydrothermal springs. Small subunit rRNA gene amplicon sequencing from eight bacterial mats was used to assess community structure. These revealed a relatively homogeneous, yet diverse bacterial community. High alpha diversity and low beta diversity indicate that these communities are likely fueled by homogeneous hydrothermal fluids. An examination of autotrophic taxa abundance indicates the potential importance of iron and sulfur inputs to the primary productivity of these mats. Chemoautotrophic potential within the mats was dominated by iron oxidation from Gallionella and Mariprofundus and by sulfur oxidation from Sulfuricurvum and Thiobacillus with an additional contribution of nitrite oxidation from Nitrospira. Metagenomic analysis showed that cbbM genes were identified as Gallionella and that aclB genes were identified as Nitrospira, further supporting these taxa as autotrophic drivers of the community. The detection of several taxa containing arsC and nirK genes suggests that arsenic detoxification and denitrification processes are likely co-occurring in addition to at least two modes of carbon fixation. These data link the importance of the detected autotrophic metabolisms driven by fluids derived from benthic hydrothermal springs to Crater Lake’s entire lentic ecosystem.

Tanshinone IIA loaded bioactive nanoemulsion for alleviation of lipopolysaccharide induced acute lung injury via inhibition of endothelial glycocalyx shedding

Acute lung injury (ALI) and its more serious form; acute respiratory distress syndrome are major causes of COVID-19 related mortality. Finding new therapeutic targets for ALI is thus of great interest. This work aimed to prepare a biocompatible nanoformulation for effective pulmonary delivery of the herbal drug; tanshinone-IIA (TSIIA) for ALI management. A nanoemulsion (NE) formulation based on bioactive natural ingredients; rhamnolipid biosurfactant and tea-tree oil, was developed using a simple ultrasonication technique, optimized by varying oil concentration and surfactant:oil ratio. The selected TSIIA-NE formulation showed 105.7 nm diameter and a PDI ∼ 0.3. EE exceeded 98 % with biphasic sustained drug release and good stability over 3-months. In-vivo efficacy was evaluated in lipopolysaccharide (LPS)-induced ALI model. TSIIA-NE (30 µg/kg) was administered once intratracheally 2 h after LPS instillation. Evaluation was performed 7days post-treatment. Pulmonary function assessment, inflammatory, oxidative stress and glycocalyx shedding markers analysis in addition to histopathological examination of lung tissue were performed. When compared to untreated rats, in-vivo efficacy study demonstrated 1.4 and 1.9-fold increases in tidal volume and minute respiratory volume, respectively, with 32 % drop in wet/dry lung weight ratio and improved levels of arterial blood gases. Lung histopathology and biochemical analysis of different biomarkers in tissue homogenate and bronchoalveolar lavage fluid indicated that treatment may ameliorate LPS‐induced ALI symptoms thorough anti‐oxidative, anti‐inflammatory effects and inhibition of glycocalyx degradation. TSIIA-NE efficacy was superior to free medication and blank-NE. The enhanced efficacy of TSIIA bioactive nanoemulsion significantly suggests the pharmacotherapeutic potential of bioactive TSIIA-NE as a promising nanoplatform for ALI.

Flow-induced glycocalyx formation and cell alignment of HUVECs compared to iPSC-derived ECs for tissue engineering applications.

The relevance of cellular in vitro models highly depends on their ability to mimic the physiological environment of the respective tissue or cell niche. Static culture conditions are often unsuitable, especially for endothelial models, since they completely neglect the physiological surface shear stress and corresponding reactions of endothelial cells (ECs) such as alignment in the direction of flow. Furthermore, formation and maturation of the glycocalyx, the essential polysaccharide layer covering all endothelial surfaces and regulating diverse processes, is highly dependent on applied fluid flow. This fragile but utterly important macromolecular layer is hard to analyze, its importance is often underestimated and accordingly neglected in many endothelial models. Therefore, we exposed human umbilical vein ECs (HUVECs) and human induced pluripotent stem cell-derived ECs (iPSC-ECs) as two relevant EC models in a side-by-side comparison to static and physiological dynamic (6.6 dyn cm−2) culture conditions. Both cell types demonstrated an elongation and alignment along the flow direction, some distinct changes in glycocalyx composition on the surface regarding the main glycosaminoglycan components heparan sulfate, chondroitin sulfate or hyaluronic acid as well as an increased and thereby improved glycocalyx thickness and functionality when cultured under homogeneous fluid flow. Thus, we were able to demonstrate the maturity of the employed iPSC-EC model regarding its ability to sense fluid flow along with the general importance of physiological shear stress for glycocalyx formation. Additionally, we investigated EC monolayer integrity with and without application of surface shear stress, revealing a comparable existence of tight junctions for all conditions and a reorganization of the cytoskeleton upon dynamic culture leading to an increased formation of focal adhesions. We then fabricated cell sheets of EC monolayers after static and dynamic culture via non-enzymatic detachment using thermoresponsive polymer coatings as culture substrates. In a first proof-of-concept we were able to transfer an aligned iPSC-EC sheet to a 3D-printed scaffold thereby making a step in the direction of vascular modelling. We envision these results to be a valuable contribution to improvements of in vitro endothelial models and vascular engineering in the future.

Sources of irregular energy density in energy–momentum squared gravity with charge

This manuscript studies the inhomogeneity in the energy density for the relativistic dynamical charged system by invoking the outcomes coming from the considered anisotropic distribution of radiating fluid. We use newly developed f(G,T2) theory, which was proposed by the addition of T2=TζξTζξ in the usual action of f(G,) gravity. We construct relativistic field equations for a specific model f(G,T2)=λT2+G(1+Gα), to examine the gravitational structure in the influence of electromagnetic filed. We use dynamical expressions and differential equations for Weyl tensor for the inspection of sources of irregularities. By exploring special cases in the non-radiating and radiating scenarios, the irregularity elements for a fluid are examined. These special cases show that modified terms and charge have a considerable impact on the fluid inhomogeneity.

Sound Radiation of a Line Source with General Time Dependence Moving Above an Interface Between Two Homogeneous Semi-Infinite Fluid Media

In this paper, the sound field due to a line source moving above a homogeneous semi-infinite fluid medium emitting an arbitrary time signal is deduced. The source moves with a constant velocity parallel to the flat interface at a fixed height. The expression for the velocity potential is obtained from the impulse response of the stationary line source by including the motion of the source in the source density function. The resulting sound field is expressed in terms of convolution integrals. The correctness of the formulas is verified by comparing them with the results known for the case of a continuous harmonic line source. Two examples, the sound field due to a delta pulse and a Gaussian pulse, are computed and presented. Finally, the relation between the solutions obtained here and the ones obtained when the source moves above an absorbing impedance surface is shown.

Comparison of very affordable immersion pump and heart-lung-machine for post mortem CT angiography in forensic pathology – A case-control study

• Identification of an alternative pump design / principle (immersion centrifugal pump) and comparison with established historical de-facto standard (roller pump). • Comparison using age-sex matched sample and quantitative aspects of vascular contrast filling. • Better result of centrifugal pump may be explained technically, in that these pumps are designed for Newtonian fluids, whereas roller pumps usually have their specific role in fluids that are not routinely pumped during post mortem computed tomography angiography. Full body post mortem CT angiography (PMCTA) in forensic medicine started on a larger scale with relatively expensive roller-pumps for what in essence seems to be a task consisting of pumping mostly homogenous contrast fluids. At considerably lower cost, centrifugal pumps are a technically powerful alternative. We compare a very affordable immersion pump (IP) with a heart lung machine (HLM) for an iodine based vascular contrast agent in a age-sex matched case-control study of 10 each. The IP outperformed the HLM, in part with statistical significance, depending on the aspect or metric that was compared. Concluding, the IP may be preferred as a useful and affordable alternative over a more expensive roller-pump.

An investigation of acoustic relocation phenomenon in a microchannel under acoustic fields

This work investigates the effects of actuation frequency and fluid properties on the relocation of miscible inhomogeneous fluids inside a microchannel under acoustic standing waves. Remarkably, we demonstrate the cases in which relocation is achieved relatively faster in the case of fluids with smaller impedance difference between them (1.5%), than in the case of fluids with larger impedance difference (10%) when actuated at an optimum frequency. Subsequently, we show that, if the impedance difference between two fluids is less, actuation of the microchannel at a single frequency is sufficient for the fast and complete relocation, whereas, in the case of larger impedance difference between the fluids, sweeping at multiple frequencies results in fast and more complete relocation compared to actuation of the system by a single frequency. Furthermore, the role of gravity in the process is also analyzed in detail.

Swimming in density-stratified fluid: study on a flapping foil

It is of interest to investigate how a swimming animal performs in a density-stratified fluid. This paper studies a simplified swimmer, a pitching NACA0015 airfoil, considering its locomotion in both homogeneous, or unstratified, and stratified fluid flows. A direct comparison is made between these two conditions through two-dimensional numerical simulations. Our numerical results show that the stratification modifies the dynamics of the pitching foil in both its wake structures and the drag force, or thrust, as well as its propulsive performance. We suggest that the effects of stratification on flapping performance or propulsive efficiency can be categorized according to the Froude number, or the level of stratification. First, in the range of high Froude numbers, notable modification of the flow structure can be observed, which however does not greatly affect the propulsive performance. Second, at a very low Froude number, i.e., Fr = 1, the propulsive efficiency drops markedly compared to its homogeneous counterpart, attributed to the pronounced internal waves induced by the strong stratification. Moreover, at a moderate Froude number Fr = 2, we find an increase in the propulsive efficiency, which can be explained by the unique variation in the wake structure. At A D = 2.50, the propulsive efficiency peaks at Fr = 2, with its efficiency 18.3% higher than its homogeneous counterpart, exhibiting a favourable influence of the stratification on a swimmer.

A novel definition of complexity in torsion based theory

Despite coming across quite effective definitions of complexity in terms of many modified theories of gravity, it still has a question about its existence in f(T) gravity, where the torsion scalar T is accountable for gravitational impacts. The emergence of complexity factor is due to division of intrinsic curvature in an orthogonal way as described by Herrera (Phys Rev D 97:044010, 2018). To initiate the analysis, we reckon the interior region is like a spherically symmetric static configuration filled by the locally anisotropic fluid and exteriorly associated with a spherical hypersurface. In this framework, we acquire the f(T) field equations and utilize the already formulated relationship between the intrinsic curvature and the conformal tensor to perform our analysis. We bring into action the definitions of the two frequently availed masses (Tolman and Misner–Sharp) for spherical composition and investigate the appealing correlation between them and the conformal tensor. The impact of the local anisotropy and the homogeneity and inhomogeneity of energy density has substantial importance in this regard. We build up some relation in terms of already defined variables and interpret the complexity as a single scalar Y_{TF}. It deduce that this factor vanished when the fluid content is homogenous and also when the impact of two anisotropic terms cancel out in the case of inhomogeneous fluid content. We determine a few definite interior solutions which fulfill the criterion of vanishing scalar Y_{TF}. Certain defined ideas in fulfillment of the vanishing complexity factor constraint, are applied for f(T) gravity.

Periodic Waves and Ligaments on the Surface of a Viscous Exponentially Stratified Fluid in a Uniform Gravity Field

The theory of singular perturbations in a unified formulation is used, for the first time, to study the propagation of two-dimensional periodic perturbations, including capillary and gravitational surface waves and accompanying ligaments in the 10−4&lt;ω&lt;103 s−1 frequency range, in a viscous continuously stratified fluid. Dispersion relations for flow constituents are given, as well as expressions for phase and group velocities for surface waves and ligaments in physically observable variables. When the wave-length reaches values of the order of the stratification scale, the liquid behaves as homogeneous. As the wave frequency approaches the buoyancy frequency, the energy transfer rate decreases: the group velocity of surface waves tends to zero, while the phase velocity tends to infinity. In limiting cases, the expressions obtained are transformed into known wave dispersion expressions for an ideal stratified or actually homogeneous fluid.

Gravothermal phase transition, black holes and space dimensionality

In the framework of gravothermal evolution of an ideal monatomic fluid, I examine the dynamical instability of the fluid sphere in ($N$+1) dimensions by exploiting Chandrasekhar's criterion to each quasistatic equilibrium along the sequence of the evolution. Once the instability is triggered, it would probably collapse into a black hole if no other interaction halts the process. From this viewpoint, the privilege of (3+1)-dimensional spacetime is manifest, as it is the marginal dimensionality in which the ideal monatomic fluid is stable but not too stable. Moreover, it is the unique dimensionality that allows stable hydrostatic equilibrium with positive cosmological constant. While all higher dimensional ($N>3$) spheres are genuinely unstable. In contrast, in (2+1)-dimensional spacetime it is too stable either in the context of Newton's theory of gravity or Einstein's general relativity. It is well known that the role of negative cosmological constant is crucial to have the Ba\~nados-Teitelboim-Zanelli (BTZ) black hole solution and the equilibrium configurations of a fluid disk. Owing to the negativeness of the cosmological constant, there is no unstable configuration for a homogeneous fluid disk to collapse into a naked singularity, which supports the cosmic censorship conjecture. However, BTZ holes of mass $\mathcal{M}_{\rm BTZ}>0$ could emerge from collapsing fluid disks. The implications of spacetime dimensionality are briefly discussed.

Behavior of weak axisymmetric fountain in homogeneous fluid with coexistent temperature and concentration effects

The behavior of weak axisymmetric fountains in homogeneous fluid with coexistent temperature and concentration effects is studied numerically over 0.25 ≤ FrT ≤ 2.0, − 0.75 ≤ N ≤ 5.0, and 20 ≤ Re ≤ 300, where FrT is the Froude number defined with temperature only, N is the buoyancy ratio representing the relative contribution of concentration to density compared to that of temperature, and Re is the Reynolds number. For each FrT, the maximum fountain height, fountain upflow width, and whole fountain width reduce with increasing N, as the combined negative buoyancy from temperature and concentration becomes stronger, while as FrT becomes larger, they increase due to the reduced overall negative buoyancy. Re has strong effects on these parameters, with a larger Re value leading to increased values of these parameters. If the overall Froude number, Fr, which is defined with combined temperature and concentration, is used instead of FrT, the existing scaling relations for the maximum fountain height for weak axisymmetric fountains with density coming from temperature only, are also applicable for the weak axisymmetric fountains with density coming from both temperature and concentration, when Fr ≲ 2.0. The quantified correlations for the characteristic parameters under the combined effects of Re and Fr have also been obtained with the numerical results.