Mounir Bou-ali | Mondragon University (original) (raw)

Papers by Mounir Bou-ali

$Research paper thumbnail of Contribution to the benchmark for ternary mixtures: Measurement of the Soret and thermodiffusion coefficients of tetralin+isobutylbenzene+n-dodecane at a composition of (0.8/0.1/0.1) mass fractions by two-color optical beam deflection$

The European physical journal. E, Soft matter, 2015

Within the framework of an international benchmark test we have performed measurements of the Sor... more Within the framework of an international benchmark test we have performed measurements of the Soret and thermodiffusion coefficients of the organic ternary mixture (0.8/0.1/0.1 mass fraction) of 1,2,3,4-tetrahydronaphthaline (THN), isobutylbenzene (IBB) and n -dodecane (n C12) at 298.15K by means of a two-color optical beam deflection technique (OBD). The data evaluation procedure is based on a least squares fitting routine for an approximate analytical solution for the Soret cell problem. The condition number of the contrast factor matrix and standard error propagation are used for an error estimation for the measured Soret and thermodiffusion coefficients. The Soret coefficients obtained are S (') T(THN) = (1.20±0.09)×10(-3) K^-1, S (') T(IBB) = (- 0.34±0.14)×10(-3) K^-1, and S (') T(nC12) = (- 0.86±0.06)×10(-3) K^-1 and the corresponding thermodiffusion coefficients are D (') T(THN) = (0.72±0.26)×10(-12) m^2(s K)^-1, D (') T(IBB) = (- 0.22±0.42)×10(-12) m^2(s ...

International Journal of Thermal Sciences, 2015

In this work we carefully measured the thermodiffusion coefficient of four ternary mixtures of 1,... more In this work we carefully measured the thermodiffusion coefficient of four ternary mixtures of 1,2,3,4tetrahydronaphthalene, isobutylbenzene and n-dodecane at 25 C and at mass fractions of: 10/80/10, 10/10/80, 40/20/40 and 45/10/45 using the thermogravitational technique. In order to determine the reproducibility of the measurements we performed three different runs for each mixture. In addition, we have also measured the thermodiffusion coefficient of 13 binary mixtures composed of these components. The obtained values of transport properties for binaries agreed with recent measurements done by optical methods and they allowed analysing the validity of an additive rule to determine the thermodiffusion coefficient of ternary mixtures from binary thermodiffusion data. A good agreement between measured and calculated values of the thermodiffusion coefficient for the four ternary mixtures studied was obtained. This work completes the thermodiffusion results for this hydrocarbon ternary mixture which has been analysed at other two compositions in previous works.

A theoretical and computational study of Soret separation of a binary mixture contained in a diff... more A theoretical and computational study of Soret separation of a binary mixture contained in a differentially heated infinite vertical annulus is presented. We first calculate the basic steady one-dimensional flow taking into account the vertical concentration gradient caused by thermodiffusion. Unstable (stable) stratification is induced at positive (negative) separation ratios. Linear stability of this basic state is performed and the critical Rayleigh number, wave number, frequency, and vertical concentration gradients are determined as functions of the separation ratio, Lewis and Parndtl numbers. It is shown that the preferred instability is axisymmetric when the induced vertical stratification is stable while it is azimuthal with unstable vertical stratification. Supercritical nonlinear computations are in agreement with linear theory and available experiments. Stability restrictions on the operation of the thermogravitational column will be discussed.

Microgravity Science and Technology, 2015

In this work the Linear Viscoelastic Behavior (LVE) of Magnetorheological Elastomers (MRE) is ana... more In this work the Linear Viscoelastic Behavior (LVE) of Magnetorheological Elastomers (MRE) is analysed according to its formulation and the working conditions. This study required both the synthesis of different MRE and the strain sweep characterization under different magnetic fields. The characterization is performed by a Physica MCR 501 Rheometer from Anton Paar, equipped with a magnetorheologic cell 70/1T MRD. In the synthesis with a given elastomeric matrix, samples with different magnetic particle concentration are studied with two types of curing conditions, under the action of a magnetic field (anisotropic MRE) and without a magnetic field (isotropic MRE). The discussed working conditions are the excitation frequency, temperature and the applied external magnetic field. The results show that the high temperatures and the MRE with higher concentration of magnetic particles restrict the LVE of MRE.

$Research paper thumbnail of Benchmark values for the Soret, thermodiffusion and molecular diffusion coefficients of the ternary mixture tetralin+isobutylbenzene+n-dodecane with 0.8-0.1-0.1 mass fraction$

The European Physical Journal E, 2015

With the aim of providing reliable benchmark values, we have measured the Soret, thermodiffusion ... more With the aim of providing reliable benchmark values, we have measured the Soret, thermodiffusion and molecular diffusion coefficients for the ternary mixture formed by 1,2,3,4-tetrahydronaphthalene, isobutylbenzene and n-dodecane for a mass fraction of 0.8-0.1-0.1 and at a temperature of 25 • C. The experimental techniques used by the six participating laboratories are Optical Digital Interferometry, Taylor Dispersion technique, Open Ended Capillary, Optical Beam Deflection, Thermogravitational technique and Sliding Symmetric Tubes technique in ground conditions and Selectable Optical Diagnostic Instrument (SODI) in microgravity conditions. The measurements obtained in the SODI installation have been analyzed independently by four laboratories. Benchmark values are proposed for the thermodiffusion and Soret coefficients and for the eigenvalues of the diffusion matrix in ground conditions, and for Soret coefficients in microgravity conditions.

2013 IEEE International Ultrasonics Symposium (IUS), 2013

Particle loaded polymers and elastomers have been largely used in different ultrasonic applicatio... more Particle loaded polymers and elastomers have been largely used in different ultrasonic applications like backing materials and matching layers because composite properties (velocity, attenuation, density and impedance) can be easily engineered by changing the filler concentration. Recently, the use of magnetic particles has been theoretically proposed as a means to produce active matching layers whose response can be modified upon the application of magnetic fields. In this paper, we propose to introduce modifications of the composite properties by using magnetic particles and applying magnetic fields during curing to establish well defined patterns in the spatial distribution of the particles within the elastomer that induce material anisotropy that effectively modify ultrasonic properties.

Thermodiffusion or the Soret effect in binary, ternary and quaternary hydrocarbon mixtures is stu... more Thermodiffusion or the Soret effect in binary, ternary and quaternary hydrocarbon mixtures is studied. Using the linear non-equilibrium thermodynamic (LNET) approach, expressions are derived for the estimation of the thermodiffusion coefficients or factors in quaternary mixtures using different approaches. New series of experimental data for binary, ternary and quaternary mixtures are used to evaluate the performance of the Firoozabadi, Kempers (Haase) and our two developed expressions based on the LNET approach. Results show that the model expressions are generally more effective for binary mixtures. In binary mixtures, the Firoozabadi model is preferred, whereas in ternary and quaternary mixtures, our developed expressions based on the LNET and the LNETeKempers combined approach are superior. Overall, we may conclude that the LNET approach, extended by the authors to ternary and quaternary mixtures, is a reliable model for less-complex systems, such as the linear hydrocarbon mixtures. The LNET approach is also flexible in that provided the required modifications are made, it may be applicable to more complex systems, such as associating mixtures, as well. It is also argued that a thermodiffusion model should be independent of the mass transfer frame of reference, as thermodiffusion coefficients are calculated at the steady state condition, where all fluxes are zero.

In this work a double yield stress model that describes the behaviour of magnetorheological (MR) ... more In this work a double yield stress model that describes the behaviour of magnetorheological (MR) fluids is presented. The first yield stress is elastic and the second yield stress is viscous, defining an initial elastic behaviour and posterior biviscous behaviour. The model presented has been validated by experimental tests realized using a rotational rheometer equipped with a parallel plates measuring

Smart Materials and Structures, 2014

In this paper, it is shown that the MR damper's power dissipation capacity is determined by the t... more In this paper, it is shown that the MR damper's power dissipation capacity is determined by the time spent in the pre-and the post-yield damping regimes. This time is determined by its design, by the MR fluid's rheological behavior and by the type of movement applied to the MR damper. To analyze those working regimes, two types of movement with different amplitudes have been applied to the MR damper at different magnetic field intensities and excitation frequencies. The first movement is an imposed harmonic movement, and in the second, power controlled unrestrained movement is obtained. These unrestrained conditions are equivalent to those the MR damper handles in a real application. For all the analyzed conditions, the obtained results have shown that when a harmonic movement is imposed on the damper, the MR fluid is forced to work in the post-yield regime for the majority of the cycle. In contrast, when the unrestrained response is measured, the pre-yield behavior becomes more significant. As a result, for equal maximum displacement, the MR damper dissipates more power when a harmonic movement is imposed compared to the unrestrained movement.

Smart Materials and Structures, 2009

This paper presents a magnetization model that endeavors to capture the change in the rheological... more This paper presents a magnetization model that endeavors to capture the change in the rheological behavior due to the application of magnetic fields to ferrofluids (FFs) and magnetorheological fluids (MRFs). Samples of Ferrotec APG 2115 FF and Lord MRF-122-2ED MRF have been tested using an Anton Paar MCR 501 rotational rheometer fitted with a parallel-plate measuring system. On the basis of the results, the FF has been modeled using the Newtonian model whereas the MRF has been adjusted using the Bingham and Herschel-Bulkley models. All three models have been extended using the herein-proposed magnetization model, that provides good adjustment of any of the models to the entire range of applied magnetic field.

Rheologica Acta, 2009

This work proposes a new numerical method for determining the shear stress, which does not need a... more This work proposes a new numerical method for determining the shear stress, which does not need any preassumption about the exact behavior of the fluid to achieve absolute data using a parallel-plate measuring system. The ability for representing different behaviors along the entire shear-rate range makes this method particularly interesting for the study of magnetorheological (MR) fluids. In this work, the conversion factors used by the rheometer for concentric-cylinder, cone-plate, and parallel-plate measuring systems are first analyzed. This analysis shows that the software used by the rheometer is not appropriate for the quantitative characterization of non-Newtonian fluids using the parallel-plate measuring system. Therefore, a new method for conversion of the parameters measured by the rheometer to the rheological parameters of the fluid is proposed; simultaneously, this new method is compared with other correction methods proposed in the literature: the Rabinowitsch-type method and the single-point method. Finally, the proposed method is applied for the quantitative characterization of an MR fluid.

Mechanism and Machine Theory, 2009

This paper presents a new test and analysis method for the characterization of the static and dyn... more This paper presents a new test and analysis method for the characterization of the static and dynamic friction in a damper. In addition, a new friction model that refers to the experimental results is presented and compared with the Coulomb, Spring-Damper, and Bouc-Wen models. The proposed model accurately represents the experimental results as well as responds to the changes on the behavior due to frequency variations.

Journal of Chemical & Engineering Data, 2012

ABSTRACT The sorption isotherm, the glass transition, and the mutual diffusion coefficient of pol... more ABSTRACT The sorption isotherm, the glass transition, and the mutual diffusion coefficient of polyacrylamide/water solutions are obtained experimentally. All of these parameters are measured in the concentrated regime by gravimetric experiments. The mutual diffusion coefficient is also measured at high solvent concentrations by the sliding symmetric tubes technique. Three different polyacrylamide batches differing in their molar mass have been characterized. The results are expressed in terms of simple empirical correlations, suitable for use in process modelization or numerical simulations.

International Journal of Thermal Sciences, 2010

Comptes Rendus Mécanique, 2013

The objective of this work is the determination of diagonal and cross-diagonal molecular diffusio... more The objective of this work is the determination of diagonal and cross-diagonal molecular diffusion coefficients in a ternary mixture, using the 'Sliding Symmetric Tubes' (SST) technique. The analyzed mixture consists of two aromatics and one normal alkane (tetrahydronaphthalene-dodecane-isobutylbenzene) with an equal mass fraction for all components (1:1:1) at 25 • C. The analytical solution corresponding to the SST technique has been successfully derived. The different fitting procedures were utilized by two scientific teams to subtract diffusion coefficients from the experimentally measured time-dependent concentration field. None of the attempts provided reliable results for the data from a single experiment. The "simplex"-based methods display reasonable results assuming that crossdiagonal coefficients are close to zero, i.e. quasi-binary and diluted mixtures. The results obtained by "trust region method" are satisfactory if the initial guess is good. To achieve better results, it is necessary to increase the number of experimental data.

The Journal of Chemical Physics, 2015

Investigation of Fickian diffusion in the ternary mixture of 1,2,3,4-tetrahydronaphthalene, isobu... more Investigation of Fickian diffusion in the ternary mixture of 1,2,3,4-tetrahydronaphthalene, isobutylbenzene, and dodecane Diffusion, thermal diffusion, and Soret coefficients and optical contrast factors of the binary mixtures of dodecane, isobutylbenzene, and 1,2,3,4-tetrahydronaphthalene J. Chem. Phys. 138, 114503 (2013); 10.1063/1.4795432

The aging processes limit useful life of lead-acid batteries. The stratification in flooded lead-... more The aging processes limit useful life of lead-acid batteries. The stratification in flooded lead-acid batteries is one of them. In this research project, an analysis of stratification is being carried out, in order to deactivate it. If that objective is achieved, the efficiency of the battery will be increased, the useful life of batteries will be prolonged and, moreover, the impact on the environment will be reduced. We have characterized the electrolyte of the battery, we have designed a test bench and initial simulations have been performed. From now on, we will continue working on experimental verification.