ISOGEOMETRIC VARIATIONAL MULTISCALE MODELING OF LAMINAR AND TURBULENT FLOW THROUGH CONCENTRIC ANNULAR PIPE

Y. Gaffari Motlagh(유세프 카퍼리 모트랩),H. T. Ahn(안형택) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.11

We present an Isogeometric variational multiscal residual-based method to solve laminar and turbulent concentric annular pipe flow. Isogeometric analysis is utilized for higher order approximation of the solution using B-spline basis functions. We first consider laminar flow and employ linear, quadratic and cubic discretizations that are C0-continuous, C1 -continuous and C2-continuous across element boundaries respectively. Next, we apply our approach to the turbulent concentric annular pipe flow. To validate our results on the turbulent flow we compare them with the available DNS data. The ability of Non-Uniform Rational B-Splines (NURBS) to exactly represent curved geometries makes NURBS- based isogeometric analysis attractive for application curved channel. Also, the curvature effect on the flow characteristics is studied in this work.

Laminar and turbulent channel flow simulation using residual based variational multi-scale method

Yousef Ghaffari Motlagh,Hyung Taek Ahn 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.2

We present a residual-based isogeometric variational multiscale method to solve laminar and turbulent channel flow. Residual-based variational multiscale method is a new finite element formulation for solving turbulent flows using a large-eddy simulation type modeling. Isogeometric analysis, a new finite element method using CAD blending functions as its basis functions, is employed for higher order approximation of the solution. First, laminar flow with Re 0.55 τ = through flat channel is considered and linear, quadratic and cubic basis functions, which are C0, C1, and C2 -continuous across element boundaries, respectively are employed and their accuracy is presented by the comparison with analytical result. Next, same methodology is applied to the turbulent channel flow with Re 180 τ = . Current results are validated by the comparison of turbulence statistics using available DNS data.

Simulation of laminar flow through eccentric annuli using isogeometric variational multiscale method

Yousef Gaffari Motlagh,이은택,안형택 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8

We present an application of the Residual-based variational multiscale (RBVMS) methodology to the computation of laminar eccentricannular pipe flow with eccentricities of 0.5 and 1. Isogeometric analysis is utilized for higher order approximation of the geometryand solution using Non-uniform rational B-splines (NURBS) functions. The ability of NURBS exactly representing curved circular geometriesmakes NURBS-based isogeometric analysis attractive for the application to the flow through the eccentric annuli. By using theexact representation of circular boundary, the limiting case of the eccentricity, i.e. the inner circular wall actually touches the outer circularwall, is successfully demonstrated.

Ultrasonic assisted photocatalytic process for degradation of ciprofloxacin using TiO2-Pd nanocomposite immobilized on pumice stone

Parisa Yekan Motlagh,Sema Akay,Berkant Kayan,Alireza Khataee 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.104 No.-

Herein, Pumice (PM)-TiO2-Pd nanocomposite as an efficient catalyst was prepared by modified sol-gelmethod and used for sonophotocatalytic removal of ciprofloxacin (CIP). Various analyses were used toinvestigate the properties of the catalysts. Based on the SEM results, the TiO2 and Pd nanoparticles onthe PM surface were immobilized regularly without aggregation. Also, the crystalline structure and functionalgroups of PM-TiO2-Pd nanocomposite were identified successfully by XRD and FTIR analyses. Thebandgap energy of 2.52, 3.17, and 3.29 eV were calculated for PM-TiO2-Pd, PM-TiO2, and PM indicatinghigher sonophotocatalytic activity of PM-TiO2-Pd nanocomposite. 79.44 % of CIP was removed within120 min of treatment time using in the optimum condition ([PM-TiO2-Pd] = 0.5 g/L, [CIP]0 = 20 mg/Land pH = 6). By adding radical scavengers like EDTA, CrO3, formic acid, and enhancers like K2S2O8 andH2O2 the degradation efficiency was as follows respectively: 37.72, 31.71, 28.29, 88.78, and 72.43%. The reusability and stability of the composite after four consecutive runs was decreased only 9.44%. Also, 8 intermediate byproducts generated under sonophotocatalytic degradation of CIP by PM-TiO2-Pdnanocomposite were identified.

Optimization of lithium separation conditions from Caspian seawater using fuzzy logic combined with dispersive liquid–liquid extraction

Romina Pourhassan Motlagh Sharemi,Abbas Rashidi,Mohammad Hassan Mallah,Jaber Safdari 한국자원공학회 2019 Geosystem engineering Vol.22 No.3

For optimization of separation conditions of lithium from the Caspian seawater, a new combination technique of liquid–liquid extraction and fuzzy logic is being used. In this research, disperser and extraction solvents, and ligand of benzo15-crown-5, have been quickly injected. It went to cloudy form solution contain small extraction solvent drops. The impact of different parameters such as the kind and concentration of benzo15-crown-5, the volume of disperser and extraction solvents, pH and extraction time have been optimized on the extraction percentage and analyzed using fuzzy logic. The effect of other metal ion on extraction percentage was also investigated. Under the optimized conditions (volume of tetrachloroethylene: 1.5 mL, volume of acetone: 120 mL, volume of benzo15-crown-5: 0.1 mL, concentration of benzo15-crown-5: 0.001 mol/L, and pH: 1), the extraction has increased to 74% for the synthesis sample and 31% for the real sample from Caspian seawater.

Prediction of Hot Deformation Flow Curves of 1.4542 Stainless Steel

Z. Sangari Motlagh,B. Tolaminejad,A. Momeni 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.8

The ability of four constitutive equations, Johnson–Cook (JC), Zerilli–Armstrong (ZA), Arrhenius-type constitutive equationsand a newly developed phenomenological model for describing the hot flow behavior of 1.4542 stainless steel was evaluated. The hot flow curves were obtained from hot compression tests in the temperature range of 900–1050 °C and at strain ratesof 0.001–1 s−1. The JC model was not able to predict the softening part of the flow curves owing to the separated effects ofstrain, strain rate and temperature on the flow stress. The original ZA model was found to be useful at large strains but theoverall consistency between the experimental and the calculated flow curves was not good. The subsequent modifications ofthe ZA model for low strain levels resulted in acceptable predictions. It is observed that the Arrhenius-type predicted flowcurves well agree with the experimental results especially at low strain rates. However, at high strain rates where the steadystate condition is shifted to large strains, some deviations were observed at low strain levels. Finally, a phenomenologicalmodel was constructed based on the nonlinear estimation of work hardening. The flow curves developed by the model couldpredict the experimental ones with satisfactory precision.

Investigating the Effects of Graphene Content and Application Method on Surface Properties of Vinyl Ester/Silica Aerogel Coatings

Kiyoumars Labani Motlagh,Javad Seyfi,Hossein Ali Khonakdar,Saeed Mortazavi 한국고분자학회 2022 Macromolecular Research Vol.30 No.5

Vinyl ester (VE) based nanocomposite coatings, loaded with an optimum content of silica aerogels, were fabricated on aluminum. Different graphene contents (1, 2, and 3% w/w) were applied via one-step and two-step spraying methods. Surface properties exhibited pronounced changes for the two-step coatings but remained nearly unchanged for the one-step coatings. Graphene was localized in the bulk of one-step coatings whereas the two-step method led to the aggregation of graphene nanoplatelets on the coating surface. Depending on the graphene content, small stacks (2 μm) to large agglomerations (20 μm) were detected on the surface of two-step coatings. The water contact angle was essentially increased from 61° for the pure VE coating to 96° and 115° upon the incorporation of silica aerogel and induction of an individual graphene layer, respectively. Such enhanced hydrophobicity was the major reason for the improved corrosion protection properties as found by Tafel polarization plots. The maximum protection efficiency was obtained for the two-step coating loaded by 2% graphene (η=99.5%). In conclusion, vinyl ester resin was found to be a great candidate for applications where high-performance coatings with improved corrosion resistance are needed. Moreover, the use of graphene, as an individual layer on the coating surface, and the utilization of silica aerogel, as a corrosion protective additive, were demonstrated to be a promising approach in real-life corrosion protection applications.

Sonocatalytic degradation of fluoroquinolone compounds of levofloxacin using titanium and zirconium oxides nanostructures supported on paper sludge/wheat husk-derived biochar

Parisa Yekan Motlagh,Reza Darvishi Cheshmeh Soltani,Zoha Pesaran,Sema Akay,Berkant Kayan,Yeojoon Yoon,Alireza Khataee 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.114 No.-

The present study aimed at treating a water medium containing pharmaceutical compounds such aslevofloxacin (LEV). For this purpose, ultrasound (US)-based degradation of LEV was catalyzed by TiO2and ZrO2 nano-catalysts supported on biochar (BC). BC was obtained from a precursor composite of papersludge and wheat husk. The application of BC-ZrO2 led to a degradation efficiency of 54.65% within60 min. When BC-TiO2 was used, a lower degradation efficiency of 49.62% was obtained at the same reactiontime. However, increasing the time to 120 min improved the sonocatalytic degradation of LEV by BCTiO2(72.88%) compared to that of BC-ZrO2 (66.42%). In the presence of H2O2 and S2O8 2, the LEV degradationefficiency of US/BC-TiO2 increased from 72.88% to 87.98% and 94.03%, respectively, and for theUS/BC-ZrO2 process, it increased from 66.42% to 76.79% and 90.14%, respectively. The addition of isopropanolcaused the most suppressive effect on the sonocatalytic degradation of LEV for both US/BCTiO2(decreasing from 72.88% to 13.99%) and US/BC-ZrO2 (decreasing from 66.42% to 16.43%) processes. The reusability test results showed an approximately 20% reduction in the sono-reactor performancewithin three consecutive experimental runs with no substantial change in the functional groups of theas-prepared sonocatalyst. Intermediates of LEV decomposed by the two sonocatalytic processes were alsoidentified.

Facile and environmentally friendly synthesis of highly efficient two-dimensional hematene nanosheets for photocatalytic applications

Parisa Yekan Motlagh,Alireza Khataee,Aydin Hassani,Yasin Orooji 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.126 No.-

Exfoliation of bulk hematite (a-Fe2O3), as an environmentally friendly, nontoxicity, and low-cost semiconductoroxide, exhibited greater photocatalytic activity under visible light irradiation. Herein, wedescribed two preparation methods of novel two-dimensional non-van der Waals hematene (2D-Hm)nanosheets including ultrasound-assisted liquid-phase exfoliation (US-Hm) and chemical-assistedliquid-phase exfoliation (CH-Hm). The photocatalytic activity of 2D-Hm nanosheets was evaluated forthe decomposition of Tetracycline (TC). Various advanced analyses were used to investigate the physicaland chemical properties of the exfoliated samples. SEM and TEM analyses confirmed the layered structuresof 2D-Hm. The crystalline structure of 2D-Hm samples was confirmed successfully by XRD analyses. After exfoliation of bulk hematite, the surface area increased remarkably from 5.73 m2/g to 24.16, and15.26 m2/g using US-Hm, and CH-Hm exfoliation methods, respectively. The photoelectrochemical photocurrentand electrochemical impedance spectroscopy (EIS) analysis indicate that 2D-Hm samples havehigher charge-transfer efficiency than bulk hematite. Additionally, the formation of hydroxyl (OH) radicalswas approved using the o-phenylenediamine (OPD) and photoluminescence (PL) analysis. The leachingiron concentration in the aqueous phase was measured within five consecutive examinations. Torecognize the intermediates formed during the degradation process, gas chromatography-mass spectrometry(GC–MS) was employed.

GENERALIZED COHOMOLOGY GROUP OF TRIANGULAR BANACH ALGEBRAS OF ORDER THREE

( Abolfazl Niazi Motlagh ),( Abasalt Bodaghi ),( Somaye Grailoo Tanha ) 호남수학회 2020 호남수학학술지 Vol.42 No.1

The main result of this article is to factorize the first (σ, τ)-cohomology group of triangular Banach algebra T of order three with coefficients in T-bimodule χ to the first (σ, τ)-cohomology groups of Banach algbras A, B and C, where σ, τ are continuous homomorphisms on T. As a direct consequence, we find necessary and sufficient conditions for T to be (σ, τ)-weakly amenable.