On the Instability of Two Dimensional Backward-Facing Step Flow using
                        Energy Gradient Method

Nowruzi, Hashem; Nourazar, S. Salman; Ghassemi, Hassan

doi:10.29252/jafm.11.01.28235

Cited by 8 publications

(9 citation statements)

References 26 publications

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“…A Figura 1 mostra o domínio geométrico que é objeto de estudo deste trabalho. Tal geometria é conhecida como Duto com Ressalto (ou no inglês, Backward-Facing Step (BFS)), onde os parâmetros mostrados na figura, com suas proporções, foram tomados de acordo com Nowruzi et al [9]. As equações do escoamento são dadas pelo conjunto das equações de Navier-Stokes incompressíveis, que são as equações da continuidade e do momento,…”

Section: Modelagem Matemáticaunclassified

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Investigação Numérica do Escoamento Incompressível em um Duto com Ressalto para ER=1,9423

Santos

Bortoli

2022

Proceeding Series of the Brazilian Society of Computational and Applied Mathematics

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Resumo. Uma simulação numérica do escoamento em um duto com ressalto, cujo raio de expansão é 1,9423, é apresentada. As equações do escoamento são dadas pelo conjunto das equações de Navier-Stokes incompressíveis. A solução do escoamento é obtida via Dinâmica dos Fluidos Computacional, usando o método de Runge-Kutta, onde as equações são discretizadas pelo método de diferenças finitas centradas. A análise dos resultados é dada para quatro valores do número de Reynolds (100, 300, 500 e 800), onde os campos do escoamento são validados com os dados da literatura através do comprimento da zona de recirculação, dos campos das velocidades e dos campos da vorticidade. Os resultados obtidos concordam com os dados da literatura.

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Section: Modelagem Matemáticaunclassified

“…Os valores obtidos neste trabalho para o comprimento da zona de recirculação são comparados na Tabela 1 com resultados obtidos na literatura [5,6,9], todos efetuados para raio de expansão ER = 1, 9423.…”

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Investigação Numérica do Escoamento Incompressível em um Duto com Ressalto para ER=1,9423

Santos

Bortoli

2022

Proceeding Series of the Brazilian Society of Computational and Applied Mathematics

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“…BFS reattachment length growing with Re is stated that as not linear as symmetrical sudden expansion. Nowruzi et al [9] used energy gradient method for simulating BFS laminar flow. Authors provide an excellent literature survey, and the flow related part are very important in respect of the present paper.…”

Section: Introductionmentioning

confidence: 99%

Numerical Forced Convection Heat Transfer of Nanofluids over Back Facing Step and Through Heated Circular Grooves

Abdulkarim¹,

Eleiwi²,

Tahseen³

et al. 2021

MMEP

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Backward facing step arrangement is a classical case for fluid dynamics and heat transfer research. It is well characterized and therefore, used for benchmarking. However, ongoing studies reveal that the geometry also provide advantages in industry, especially in combustion and burners. This work utilizes computational fluid dynamics to investigate a specific laminar back facing step flow heat transfer case. Aluminium oxide nano particles are considered as an additive to water base fluid, forming nanofluid with different volumetric concentrations. Laminar flow passes a back facing step and encounters three circular grooves at bottom surface. All surfaces are adiabatic except the grooves. Constant surface temperature applies to the grooves. According to the simulation results, a separation bubble after back facing step and a reattachment point occur. Grooves alter expected wake due to physical and thermal interference. Investigation parameters are nano-particle concentration and Reynolds number. Reynolds number changes between 10 and 250. Nano particle volume fraction percentage changes between 2 and 6 percent. Sectional heating downstream of the step poses interesting heat flux in the presence of Aluminium oxide nano-particle concentrations. There is a pseudo-linear relationship between parameters and heat transfer. Combined effects of enhanced thermal conductivity and secondary flow structures are seen. As expected, thermal convection increases as flow velocity and nano-particle concentrations increase. Heat flux and accordingly Nusselt number are highly affected from Reynolds number since flow structure changes dramatically. Also, direct proportion is seen between nano-particle concentration and enhanced convection.

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“…He proposed that the dimensionless parameter in energy gradient method especially the energy profiles could provide a satisfactory prediction for the transition. Nowruzi et al (2018) investigated the flow instability of a backward facing step flow with the energy gradient method, and valuated the local velocity, vorticity as well as the energy gradient function. Zheng et al (2016Zheng et al ( , 2018 investigated the blade-tongue interaction and found that this interaction intensified the local pressure fluctuation which further intensified the local flow stability.…”

Section: Introductionmentioning

confidence: 99%

Study of Flow Instability in a Miniature Centrifugal Pump Based on Energy Gradient Method

Chen

Dou

et al. 2019

JAFM

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Flow instability in a miniature centrifugal pump is numerically simulated with the RANS equations and the SST k-ω turbulence model. The energy gradient method is adopted to analyze the flow instability at design load and two off-design loads, and the results are compared with those analyzed by Q-criterion. The regions with large magnitude of energy gradient function (K) indicate pronounced turbulent intensity and poor flow stability. Internal flow stability is investigated in details for both the near blade surfaces region and the impeller passages.To study the mechanism of energy gradient method, internal flow parameters such as the velocity and total pressure, the transverse gradient of total mechanical energy and the work done by shear stresses are investigated respectively. The results show that the energy dissipation reaches its maximum around the leading edge of suction surface. The value of the energy gradient function K presents a different magnitude for the near blade surfaces region and the impeller passages, and the K in the impeller passage is much larger. Regions with maximum of the work done by shear stresses are concentrated on the suction surface, regions with large transverse gradient of total mechanical energy is concentrated on the hub surfaces or shroud surfaces. It is further found that the K can reflect the influence of the outer boundaries of vortex on the flow near blade surface.

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On the Instability of Two Dimensional Backward-Facing Step Flow using Energy Gradient Method

Cited by 8 publications

References 26 publications

Investigação Numérica do Escoamento Incompressível em um Duto com Ressalto para ER=1,9423

Investigação Numérica do Escoamento Incompressível em um Duto com Ressalto para ER=1,9423

Numerical Forced Convection Heat Transfer of Nanofluids over Back Facing Step and Through Heated Circular Grooves

Study of Flow Instability in a Miniature Centrifugal Pump Based on Energy Gradient Method

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