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Research Papers: Flows in Complex Systems

Efficient Computational Fluid Dynamics Model for Transient Laminar Flow Modeling: Pressure Wave Propagation and Velocity Profile Changes

[+] Author and Article Information
Nuno M. C. Martins

CERIS,
Instituto Superior Técnico,
Universidade de Lisboa,
Av. Rovisco Pais 1,
Lisboa 1049-001, Portugal
e-mail: nunomiguelmartins@tecnico.ulisboa.pt

Bruno Brunone

Department of Civil and Environmental
Engineering,
University of Perugia,
Via G. Duranti,
Perugia 93- 06125, Italy
e-mail: bruno.brunone@unipg.it

Silvia Meniconi

Department of Civil and Environmental
Engineering,
University of Perugia,
Via G. Duranti,
Perugia 93-06125, Italy
e-mail: silvia.meniconi@unipg.it

Helena M. Ramos

CERIS,
Instituto Superior Técnico,
Universidade de Lisboa, Av. Rovisco Pais 1,
Lisboa 1049-001, Portugal
e-mail: helena.ramos@tecnico.ulisboa.pt

Dídia I. C. Covas

CERIS,
Instituto Superior Técnico,
Universidade de Lisboa,
Av. Rovisco Pais 1,
Lisboa 1049-001, Portugal
e-mail: didia.covas@tecnico.ulisboa.pt

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received January 31, 2017; final manuscript received July 17, 2017; published online September 20, 2017. Assoc. Editor: Francine Battaglia.

J. Fluids Eng 140(1), 011102 (Sep 20, 2017) (9 pages) Paper No: FE-17-1064; doi: 10.1115/1.4037504 History: Received January 31, 2017; Revised July 17, 2017

In this paper, the analysis of fast laminar transients in pressurized pipes is developed using a computational fluid dynamics (CFD) model, combined with the Zielke model and laboratory data. The systematic verification of the performance of the CFD model executed in the first part of the paper allows defining the most efficient set of the discretization parameters capable of capturing the main features of the examined transient. In this framework, the crucial role of radial discretization is pointed out. In the second part of the paper, the refined and efficient CFD model is used to examine some aspects of interest for understanding the dynamics of transients. Specifically, the uniformity of the instantaneous pressure distributions along the pipe radius, which validates the results of the most popular quasi-two-dimensional (2D) models, has been revealed. Moreover, it has been shown that the strongest link between the wall shear stress and the axial component of the velocity occurs in the region close to the pipe wall as well as that the time-shift between the wall shear stress and the local instantaneous flow acceleration increases significantly as time elapses.

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References

Figures

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Fig. 1

Steady-state flow: 1 − NSE index versus the number of nodes of each analyzed mesh (numbers indicate the rank of Table 2)

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Fig. 2

Unsteady-state wall shear stress by the steady-state best-ranked mesh versus the Zielke model at the pipe midsection

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Fig. 3

Unsteady-state wall shear stress sensitivity analysis at the midsection: La analysis (La = 150, 1500, and 3500; Lr = 65)

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Fig. 4

Unsteady-state wall shear stress sensitivity analysis at the midsection: Lr analysis (Lr = 50, 65, and 70; La = 1500)

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Fig. 5

Unsteady-state wall shear stress and mean velocity at the pipe wall (midsection) for the most representative meshes (La = 1500): (a) Lr = 105, (b) Lr = 130, (c) Lr = 260, and (d) Lr = 390

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Fig. 6

CFD results (piezometric head, H) versus laboratory data at the pipe mid- and end-sections

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Fig. 7

CFD results at the pipe midsection (from Fig. 6): (a) pressure trace and (b) pressure distribution in the pipe section at five selected instants of time

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Fig. 8

CFD results (mean velocity, V) at the pipe mid- and end-sections

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Fig. 9

CFD velocity profiles during the transient event at the pipe midsection

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Fig. 10

CFD axial velocity time-histories at different distances from the wall, at the pipe midsection, for yw = 10%R to 50%R

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Fig. 11

CFD axial velocity time-histories at different distances from the wall, at the pipe midsection, for yw = 2%R to 10%R

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Fig. 12

CFD axial velocity time-histories at different distances from the wall, at the pipe midsection, for yw = 0.4%R to 2%R

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Fig. 13

CFD dimensionless local acceleration and wall shear stress at the pipe midsection

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Fig. 14

Occurrence time of dimensionless local acceleration and wall shear stress peaks at the mid-pipe section: (a) cumulative and (b) absolute time-shifts

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