37 research outputs found
Transient conjugate free convection within flexible enclosure having discrete heat source
No full textTransient conjugate free convection in flexible enclosure is examined numerically. Isoflux heat sources are mounted in a left wall of finite thermal conductivity while a right wall is assumed to be hyper-flexible. The finite element method (FEM) is adopted to solve the governing partial differential equations, an arbitrary Lagrangian–Eulerian (ALE) approach inherent in the unstructured mesh. The governing parameters under consideration are: the number of the heat source, 1 ≤ n ≤ 3 , the thickness of the heat source, 0 ≤ a ≤ 0 . 25 , and the Rayleigh number, 10 5 ≤ Ra ≤ 10 8 . It is determined that the development of conjugate convection heat transfer experiences through an initial phase, a transition phase, and a steady state phase. Each phase interval is shifted by adjusting the thickness of the heat source. Higher number and thicker of heat source cases had an ignorant effect on the shape of the flexible wall, but they tend to suppress the heat transfer rate. Increasing the block amplitude by 25% for n = 1 , 2 , 3 results in reductions of the values of Nu ¯ to 24%, 20%, and 28% respectively
A numerical study on natural convection in a square inclined porous enclosure filled with an Ag nanoliquids
No full textPENGARUH PENERAPAN PENDEKATAN REALISTIC MATHEMATICS EDUCATION (RME) TERHADAP KEMAMPUAN PEMECAHAN MASALAH MATEMATIS DITINJAU DARI GAYA BELAJAR SISWA
No full textPenelitian ini bertujuan untuk mengetahui terdapat atau tidaknya pengaruh penerapan pendekatan Realistic Mathematics Education (RME) terhadap kemampuan pemecahan masalah matematis ditinjau dari gaya belajar siswa. Penelitian ini merupakan penelitian yang menggunakan desain factorial experiment. Populasi dalam penelitian ini adalah seluruh siswa kelas VII SMP Negeri 2 Pekanbaru tahun ajaran 2024/2025. Sampel penelitian ini dipilih dengan menggunakan cluster random sampling, terpilih kelas VII.2 sebagai kelas eksperimen dan kelas VII.1 sebagai kelas kontrol. Adapun teknik pengumpulan data yang digunakan pada penelitian ini adalah tes, angket, observasi dan dokumentasi. Instrumen pengumpulan data yang digunakan adalah soal tes kemampuan pemecahan masalah matematis, website tes gaya belajar Aku Pintar, lembar observasi dan foto pelaksanaan kegiatan penelitian. Sedangkan teknik analisis data yang digunakan adalah uji anova dua arah. Berdasarkan hasil analisis data, dapat diambil kesimpulan bahwa: 1) Terdapat pengaruh kemampuan pemecahan masalah matematis antara siswa yang belajar menggunakan pendekatan Realistic Mathematics Education (RME) dengan siswa yang belajar menggunakan pembelajaran konvensional. 2) Terdapat pengaruh kemampuan pemecahan masalah matematis antara siswa yang memiliki gaya belajar visual, auditori dan kinestetik. 3) Tidak terdapat pengaruh interaksi antara pendekatan pembelajaran dan gaya belajar terhadap kemampuan pemecahan masalah matematis siswa. Dengan demikian, secara umum dapat disimpulkan bahwa pendekatan Realistic Mathematics Education (RME) berpengaruh terhadap kemampuan pemecahan masalah matematis ditinjau dari gaya belajar siswa SMP Negeri 2 Pekanbaru
Unsteady free convection in a composite enclosure having flexible wall
No full textTransient free convection in a composite enclosure having a cold flexible plate and a hot rigid plate is simulated numerically. It is assumed that the flexible plate is hyper-elastic. A porous layer with various sizes and permeabilities is attached to the rigid plate. The enclosure is filled with water. Fluid flow in the fluid domain was governed by the Navier–Stokes equations, and the flow within a saturated porous layer was governed by the Brinkman-Forchheimer extended Darcy model. The unsteady continuity, momentum, and energy equations are solved using the Arbitrary-Lagrangian-Eulerian (ALE) approach based on the fluid-structure interaction (FSI). It is found that the development of convective flow goes through initial, transitional, and stationary states. Each state interval is shifted by varying the Darcy number and Rayleigh number. In the transitional state, the deformation of the flexible parts reaches its maximum bending. The profile of the flexible plate at steady state is in a sinusoidal shape for the non-Darcy regime, while it is in an asymmetric parabolic shape for the Darcy regime. The steady state is reached for Da → ∞ , Da = 10 − 3 , and Da = 10 − 5 before τ = 0 . 061 , 0 . 065 , 0 . 091
Conjugate Heat Transfer in Rayleigh-Bénard Convection in a Square Enclosure
No full textConjugate natural convection-conduction heat transfer in a square enclosure with a finite wall thickness is studied numerically in the present paper. The governing parameters considered are the Rayleigh number (5 × 10 3 ≤ Ra ≤ 10 6 ), the wall-to-fluid thermal conductivity ratio (0.5 ≤ Kr ≤ 10), and the ratio of wall thickness to its height (0.2 ≤ ≤ 0.4). The staggered grid arrangement together with MAC method was employed to solve the governing equations. It is found that the fluid flow and the heat transfer can be controlled by the thickness of the bottom wall, the thermal conductivity ratio, and the Rayleigh number
Use of Finite Element Method for Free Convection of Nanofluids between a Rectangular Enclosure and a Sinusoidal Cylinder Using Buongiorno’s Two-Phase Model
No full textIn this study, the free convection of nanofluids between a rectangular enclosure and a sinusoidal cylinder is numerically analyzed using the finite element method (FEM). Two-phase Buongiorno’s formulation was used to model the fluid layer, and Brinkman-Forchheimer equation was used to formulate the porous layer. The enclosure has a low temperature, while the cylinder is maintained at a high temperature. The governing equations are expressed in PDEs and converted into weak formulations (Galerkin FEM). In numerical simulations, the average concentration, the amplitude of undulated cylinder, the number of undulated, and the Rayleigh number are investigated. It is observed that the homogeneous nanofluid model could be valid for low heating intensity with higher waviness frequency and/or higher amplitude. The higher the alumina concentration, the higher the heat transfer rate. The heat transfer rate can be boosted by up to 13% by suspending 1% alumina particles. The heat transfer enhancement decreases with increasing the amplitude and/or increasing the waviness number
Conjugate Heat Transfer in Rayleigh-Bénard Convection in a Square Enclosure
No full textConjugate natural convection-conduction heat transfer in a square enclosure with a finite wall thickness is studied numerically in the present paper. The governing parameters considered are the Rayleigh number 5×103≤Ra≤106, the wall-to-fluid thermal conductivity ratio 0.5≤Kr≤10, and the ratio of wall thickness to its height 0.2≤D≤0.4. The staggered grid arrangement together with MAC method was employed to solve the governing equations. It is found that the fluid flow and the heat transfer can be controlled by the thickness of the bottom wall, the thermal conductivity ratio, and the Rayleigh number
The Effect Chemical Reaction to Free Convection of Micropolar Fluid in a Vertical Channel
No full textCOMPUTATION OF NATURAL CONVECTION IN A POROUS PARALLELOGRAMMIC ENCLOSURE WITH A MAGNETIC FIELD
No full textDetailed numerical calculations are presented in this paper for natural convection in a porous parallelogrammic enclosure with a magnetic field. The inclined walls are maintained isothermally at different temperatures. The top and bottom horizontal straight walls are kept adiabatic. To simplify the effort in matching the grid mesh with the inclined walls of the parallelogrammic region/geometry, the computational domain is mapped onto a rectangular shape using a non-linear axis transformation. Transport equations are modeled by a stream-vorticity formulation then expressed in the new coordinate system and solved numerically by a finite difference method. Based upon the numerical predictions, we found the convection modes within the enclosure depended upon the Rayleigh number and the inclination angle. As the value of magnetic field is made larger, the strength of the heat transfer is progressively suppressed. Tuning the inclination angle decreases the heat transfer performance
Flow Reversal of Fully Developed Mixed Convection in a Vertical Channel with Chemical Reaction
No full textThe present analysis is concerned with the criteria for the onset of flow reversal
of the fully developed mixed convection in a vertical channel under the effect of the chemical reaction. The governing equations and the
critical values of the buoyancy force are solved and calculated numerically via MAPLE.
Parameter zones for the occurrence of reversed flow are presented. The exothermic
chemical reaction is found to enhance the flow reversal and made flow reversal possible
for symmetrical walls temperature
