CN110059399A - A kind of method of numerical simulation plunging nappe - Google Patents
A kind of method of numerical simulation plunging nappe Download PDFInfo
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- CN110059399A CN110059399A CN201910297894.8A CN201910297894A CN110059399A CN 110059399 A CN110059399 A CN 110059399A CN 201910297894 A CN201910297894 A CN 201910297894A CN 110059399 A CN110059399 A CN 110059399A
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Abstract
The present invention relates to a kind of methods of numerical simulation plunging nappe comprising following steps: 1 establishes overflow weir model and then the structural grid of subdivision and boundary condition is arranged；2 establish plunging nappe iterative calculation model comprising establish Turbulent Equations, Two-phase flow's separation, primary condition and relaxation factor；3 establish numerical simulation result processing model comprising setting color bar parameter, water volume fraction and two-phase display parameters.The present invention can fast, accurately simulate the motion state of plunging nappe, provide reference for the development of overflow Diffusion Law Basic Mechanism and practical engineering application.
Description
Technical field
The invention belongs to plunging nappe simulation application fields, and in particular to a kind of method of numerical simulation plunging nappe.
Background technique
Down stream is that water flow stream of postponing is transitioned into torrent, the sudden turn of events flow phenomenon that the water surface sharply lands, when water body is in side wall top surface
It flows upwardly to the outer peripheral depth of water in the process to become smaller, until the depth of water is reduced to critical depth of water when water falls bank section, streamflow regime becomes
For critical flow, water body partical gravity and air drag irrelevancy weigh after being fallen bank section, cause water flow to accelerate, streamflow regime becomes
Torrent.It is known as overflow from the water body for falling bank section whereabouts；Overflow pick-up point and the outer peripheral vertical range of swimming pool side wall are water
Tongue length.
In recent years hydraulics researcher for weir flow, water falls and overflow expands research.University Of Tianjin Liu in 1989
Xuan Lie etc. analyzes and researches to aeration of three-dimensional jet diffusion property, and close shot stereo and resistance-type are used in test
Two kinds of measurement methods of aeration instrument obtain relational expression to the relationship overflow section aqueous concentration, evolution with distance and parameter, simultaneously
Ternary overflow vertical, horizontal Diffusion Law is obtained, the criterion for determining overflow dimension is provided, for the movement of further research aerated nappe
Trajectory analysis provides reference value；The happy U.S.A of Changsha nonferrous metallurgy design institute in 1999 holds the correlation for having studied drop water scenery design
Problem, i.e. drop flow rate calculation check overflow length, elaborate the flow rate calculation formula of general broad-crested weir free discharge, fall
Overflow calculating formula of length；Diao Ming army, Sichuan University in 2003 etc. uses VOF method numerical simulation flip trajectory bucket water-air two phase flows,
The aerial trajectory line of jet stream and the table of cushion pool are had studied, streamline, pressure, flow field, the turbulent fluctuation energy of computational domain have been obtained
And the distribution of turbulent fluctuation dissipative shock wave, and analog result is verified with physical model, numerical simulation result and physical model experiment
Data coincide it is good, illustrate to simulate aerial jet flow and cushion pool fluidised form using two-phase flow model and VOF method be can
Capable；2017 Nian Guikan institute Yuan Qiang etc. have studied application of the flip trajectory bucket two-phase flow numerical simulation in the improvement of old dam, pass through VOF
Model and PISO algorithm have carried out water-air two phase flows Two-dimensional Unsteady numerical value from upstream reservoir area to the water cushion pool downstream pool to flip trajectory bucket
Simulation obtains the impact condition of the lower stream that sluices.
The comprehensive overflow research achievement discovery delivered, researcher carry out overflow movement rule in the method for traditional measurement
Rule, establishes physical model and measurement data heavy workload, elapsed time, and measurement result has biggish error.In recent years, part
Gradually numerical simulation trajectory nappe moves for colleges and universities or R&D institution, but result is not space angle, but two dimension choose stream or with
It studies based on flow field and pressure, so currently without the effective technique study overflow characteristics of motion.
In engineering and life, the overflow characteristics of motion is of wide application, and reservoir water is arrived greatly in the small setting to landscape waterfall
The construction that dam is built in flood discharge requires the characteristics of motion for understanding overflow, so needing to research and develop a kind of pair of plunging nappe
Quickly, analogy method accurately, economic provides reference to the theoretical research of the overflow characteristics of motion and practical implementation.
Summary of the invention
Technical problem to be solved by the present invention lies in providing a kind of method of numerical simulation plunging nappe, can quickly,
The motion state of accurate simulation plunging nappe provides ginseng for the development of overflow Diffusion Law Basic Mechanism and practical engineering application
It examines.
To achieve the above object, technical solution of the present invention the following steps are included:
(1) overflow weir model and then the structural grid of subdivision are established and boundary condition is set；
(2) plunging nappe iterative calculation model is established comprising establish Turbulent Equations, Two-phase flow's separation, primary condition and relaxation
The factor；
(3) numerical simulation result processing model is established comprising setting color bar parameter, water volume fraction and two-phase display ginseng
Number.
Further, in step (1), the overflow weir model includes overflow weir region (12) and and the overflow of tetragonal body
Weir region (12) is vertically and the overflow region (13) of the tetragonal body of top connection, the weir crest of the overflow weir region (12) are water
It is flat；The connected component of overflow weir region (12) and overflow region (13) is interface (6)；
The overflow weir region (12) includes interface (6) and the import (1) for being located at the four directions body region front and rear sides face,
Be located at left and right sides overflow weir region left side (2) and overflow weir region right side (3) and be located at upper and lower end face
Overflow weir region top surface (4) and weir crest (5)；The overflow region (13) includes being located at the four directions body region front and rear sides
The overflow region leading flank (8) and interface (6) in face, the weir body (7) being located at below interface (6), are located at left and right two
Overflow region left side (9), overflow region right side (10) and the overflow region top surface positioned at upper and lower end faces of side
(14) and (11) are exported.
Further, in step (1), the setting method of boundary condition are as follows:
The import (1) is set as flow velocity entrance or traffic ingress；Overflow weir region left side (2), overflow weir region are right
Side (3), weir crest (5), weir body (7) are set as wall, overflow weir region top surface (4), overflow region leading flank (8), overflow
Region left side (9), overflow region right side (10) are set as pressure export, and the interface (6) is set as inside face.
Further, the value of the height (D) in the overflow weir region 12 is greater than the value that H is calculated according to weir formula,
The weir formula are as follows:
,
Q is water flow；B is the width (F) of the weir weir Kuan Ji body (7)；G is acceleration of gravity；H is weir head；M is weir flow system
Number, h are the height (C) of weir body (7),
H value, the value of further setting height D can be calculated according to presetting overflow flow Q；
The length (E) of the overflow region (13) is that the value setting of L is obtained according to following calculation formula,
mFor weir flow coefficient；H is the height (C) of weir body (7)；HFor weir head, can be calculated according to presetting overflow flow Q
H value.
Further, in step (2), the relaxation factor includes pressure, density, physical strength, momentum, turbulent fluctuation energy, turbulent fluctuation consumption
Dissipate rate, turbulent viscosity, value sets gradually as 0.0 ~ 0.3,0.0 ~ 1.0,0.0 ~ 1.0,0.0 ~ 0.7,0.0 ~ 0.8,0.0 ~ 0.8,
0.0~1.0。
Further, in step (2), the Turbulent Equations are turbulent flow k- ε model；The Two-phase flow's separation is Volume
Of Fluid model or Mixture model or Eulerian model, and it is arranged that water is the first phase, air is the second phase.
Further, in step (2), the primary condition is set as flow velocity being set as 1 flow velocity of import or flow, water volume
Score be set as 0, volume of air score be set as 1, temperature setting be 298 ~ 300 K, turbulent fluctuation energy and disorderly kinetic energy dissipation rate according tok
Equation andεEquation calculation.
Further, in step (3), the color bar parameter is set as 0.0 ~ 1.0, and color bar number is set as 2.0 ~
40.0；
In step (3), the water volume fraction is set as 0.1 ~ 1.0, and the two-phase display parameters are set as water and air.
Further, establish in step (1) and imitate the overflow weir model that plunging nappe generates topography, after drafting and to its into
The structural grid of row subdivision and the speed import that overflow is set；
Step (2) carries out space integral to each mesh point in step (1), and the flow velocity or flow of the import of overflow speed is arranged, into
Row iteration calculates；
Step (3) exports the result after step (2) iterative calculation convergence by image processing software, and it is default to obtain step (2)
Overflow form under flow velocity or flow.
Further, the overflow weir model in step (1) carries out in computer modeling software；This is overflow after the completion of modeling
It flows weir model to import in hydrodynamics Digital calculation modelling software, carries out plunging nappe iterative calculation, will be calculated after stable convergence
As a result it imports in PaintShop, exports result or dynamic effect after adjusting the display effect of numerical simulation result.
Good effect of the present invention is as follows:
The present invention can simulate the motion state of landscape drop moisture film, artificial waterfall, flood discharge overflow by numerical generation image,
Analog result can show flow velocity or flow, pressure, the moisture content, thickness of any position at any time such as moisture film, waterfall, overflow
The hydraulic informations such as degree, can for landscape drop, artificial waterfall, flood discharge overflow design or when quantitative study provide basic data and
Analyze foundation.It should be pointed out that the present invention can be preset drop moisture film, artificial waterfall, flood discharge overflow effect when institute out
The flow needed provides important ginseng to adjust valve opening when selecting pump with design flood discharge overflow when design drop moisture film, artificial waterfall
It examines.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of overflow weir model of the present invention；
Fig. 2 is the schematic diagram after the structural grid of overflow weir model facetization of the present invention；
Fig. 3 is the schematic diagram of size code in overflow weir model of the present invention；
Fig. 4 is that the present invention in discharge per unit width is 0.00150 m3Plunging nappe state diagram when/s；
Fig. 5 is that the present invention in discharge per unit width is 0.00155 m3Plunging nappe state diagram when/s；
Fig. 6 is that the present invention in discharge per unit width is 0.00156 m3Plunging nappe state diagram when/s；
Fig. 7 is that the present invention in discharge per unit width is 0.00157 m3Plunging nappe state diagram when/s；
Fig. 8 is that the present invention in discharge per unit width is 0.00158 m3Plunging nappe state diagram when/s；
Fig. 9 is that the present invention in discharge per unit width is 0.00159m3Plunging nappe state diagram when/s；
Figure 10 is that the present invention in discharge per unit width is 0.00160 m3Plunging nappe state diagram when/s；
Figure 11 is that the present invention in discharge per unit width is 0.001700 m3Plunging nappe state diagram when/s；
Figure 12 is that the present invention in discharge per unit width is 0.00200m3Plunging nappe state diagram when/s.
Specific embodiment
The present invention program is further described and is explained with reference to the accompanying drawing.
As shown in Figure 1-3, the present invention provides a kind of methods of numerical simulation plunging nappe comprising following steps:
(1) it establishes overflow weir model and to the structural grid of overflow weir model facetization and boundary condition then is set.
Overflow weir model is the formation topography for imitating practical down stream, draw out can from generate down stream basic topography shape,
As shown in Figure 1, the overflow weir model specifically:
The overflow weir model includes the overflow weir region 12 of tetragonal body and vertical and top is connected to overflow weir region 12
The overflow region 13 of tetragonal body, the weir crest in the overflow weir region 12 are level；The company in overflow weir region 12 and overflow region 13
Logical part is interface 6；
The overflow weir region 12 includes interface 6 and the import 1 for being located at the four directions body region front and rear sides face, respectively position
In the overflow weir region left side 2 of left and right sides and overflow weir region right side 3 and positioned at the overflow weir area of upper and lower end face
Domain top surface 4 and weir crest 5；The overflow region 13 includes being located on front side of the overflow region in the four directions body region front and rear sides face
Face 8 and interface 6, the weir body 7 positioned at 6 lower section of interface, are located at overflow region left side 9, the water of left and right sides
Tongue region domain right side 10 and positioned at upper and lower end faces overflow region top surface 14 and outlet 11.
Down stream occurs Shi Weishui and enters overflow weir from import 1, reaches overflow weir region 12, then flows further through interface
6, it finally falls, is flowed out from outlet 11.
In step (1), the setting method of boundary condition are as follows:
The import 1 is set as flow velocity entrance or traffic ingress；Overflow weir region left side 2, overflow weir region right side
3, weir crest 5, weir body 7 are set as wall, overflow weir region top surface 4, overflow region leading flank 8, overflow region left side 9, water
Tongue region domain right side 10 is set as pressure export, and the interface 6 is set as inside face.
(2) establish plunging nappe iterative calculation model comprising establish Turbulent Equations, Two-phase flow's separation, primary condition and
Relaxation factor；
The Turbulent Equations be turbulent flow k- ε model comprising continuity equation, the equation of momentum,kEquation andεEquation.The turbulent flow
K- ε model is prior art model.
The Two-phase flow's separation is Volume of Fluid model or Mixture model or Eulerian model, and is arranged
Water is the first phase, air is the second phase.
The primary condition is set as being that 1 flow velocity of import or flow, water volume fraction are set as 0, volume of air by flow velocity
Score be set as 1, temperature setting be 298 ~ 300 K, turbulent fluctuation energy and disorderly kinetic energy dissipation rate according tokEquation andεEquation calculation.
The relaxation factor includes pressure, density, physical strength, momentum, turbulent fluctuation energy, turbulent fluctuation dissipative shock wave, turbulent viscosity, value according to
It is secondary to be set as 0.0 ~ 0.3,0.0 ~ 1.0,0.0 ~ 1.0,0.0 ~ 0.7,0.0 ~ 0.8,0.0 ~ 0.8,0.0 ~ 1.0.
It is only operated in this parameter area provided by the invention, iterative numerical could effectively restrain.Due to stream
Nonlinear equation is solved in mechanics, in solution procedure, control variable variation be it is very necessary, this just passes through relaxation
For the factor come what is realized, it controls the variation of variable in each iteration, that is to say, that the new value of variable is that initial value adds variable quantity
Multiplied by relaxation factor.Such as:
A1=A0+B*DETA
Wherein, A1 is new value, and A0 is initial value, and B is relaxation factor, and DETA is variable quantity.Relaxation factor can control convergent speed
With the convergent situation of improvement.Relaxation factor is equal to 1, is equivalent to without relaxation factor；Relaxation factor is greater than 1, is overrelaxed factor,
Accelerate convergence rate；For relaxation factor less than 1, relaxation factor improves convergent condition.In general, everybody is bad in convergence
When, using a lesser relaxation factor.Inside Fluent is to owe relaxation, mainly prevents twice that iterative value difference is too
Cause to dissipate greatly.The value of relaxation factor between 0~1, smaller expression change between iterative value twice it is smaller, it is also more stable,
But it restrains also slower.Iteration meter may be implemented suitable for the relaxation factor of alternative manner of the present invention in providing for the invention
That calculates goes on smoothly and can generate convergent data result.
(3) numerical simulation result processing model is established comprising setting color bar parameter, water volume fraction and two-phase are shown
Parameter.
The color bar parameter is set as 0.0 ~ 1.0, and color bar number is set as 2.0 ~ 40.0.Design parameter can be according to image
To adjust, reaching image being capable of the identification easily differentiated of complete display for display.
The water volume fraction is set as 0.1 ~ 1.0, and the two-phase display parameters are set as water and air.
According to the judgment method of image are as follows: iterate to calculate curve for drop overflow numerical simulation, be one under normal circumstances
Pulsation curves, with the increase of iterative calculation number, curve also can be elongated, to see whether pulsation curves reduce or overall at this time
Reduce, if the trend for not dropping or rising occur in pulsation curves, calculating can generally dissipate.In addition iterative calculation curve corresponds to residual
Difference, during calculating, residual values are also to stablize decline, if residual values decline always, numerical value calculates generally can be steady
Fixed convergence, but when residual values occur and being increased beyond 250, numerical value calculating can generally dissipate.
If to stop calculating immediately when therefore discovery iterativecurve or residual values occur abnormal, turn down relaxation factor or
Person's re-optimization numerical model and computation model.
Overflow weir model in step (1) of the present invention carries out in computer modeling software, such as GAMBIT or ICEM soft
It part but is not limited to carry out in these softwares.The overflow weir model is imported into hydrodynamics Digital calculation modelling software after the completion of modeling
In, such as FLUENT software, but it is not limited to FLUENT software.Plunging nappe is carried out in hydrodynamics Digital calculation modelling software
Iterative calculation imports calculated result in PaintShop after stable convergence, such as TECPLOT software, but is not limited to
TECPLOT software exports result or dynamic effect after adjusting the display effect of numerical simulation result in PaintShop.
Thinking of the invention are as follows: established in step (1) and imitate the overflow weir model that plunging nappe generates topography, after drafting simultaneously
The structural grid of subdivision is carried out to it and the speed import of overflow is set；
Step (2) carries out space integral to each mesh point in step (1), and the flow velocity or flow of the import of overflow speed is arranged, into
Row iteration calculates；
Step (3) exports the result after step (2) iterative calculation convergence by image processing software, and it is default to obtain step (2)
Overflow form under flow velocity or flow.
The present invention has finally obtained specific plunging nappe figure, in this figure the form of overflow can reflect in practice, when
When to 1 flow velocity of exit port or flow, which type of overflow can be corresponded to, it can be with artificial in guiding life and industry, such as life
Waterfall, through the invention it is known that the speed import of the primary condition setting overflow of step (1), step (2)
The flow velocity or flow of overflow speed import are set in setting, by step (2) to the space integral and iterative calculation of each mesh point
And image is generated by step (3), it is known which type of overflow formed under setting flow velocity or flow, reality can be instructed
Optimum overflow form is obtained with least water.
It in dam flood discharge, can instruct by the method for the invention, it is known that whether dam meets the effect of flood control.
The present invention can simulate the movement of landscape drop moisture film, artificial waterfall, flood discharge overflow by numerical generation image
State, analog result can show the flow velocity or flow, pressure of any position, aqueous at any time such as moisture film, waterfall, overflow
The hydraulic informations such as rate, thickness, can be to provide basis in landscape drop, artificial waterfall, the design of flood discharge overflow or when quantitative study
Data and analysis foundation.It should be pointed out that the present invention can be preset drop moisture film, artificial waterfall, flood discharge overflow effect out
Required flow when fruit, to select pump to provide with adjustment valve opening when design flood discharge overflow when design drop moisture film, artificial waterfall
Important references.
Embodiment 1
(1) overflow weir model is drawn and established to the present embodiment, the overflow weir model includes tetragonal body in GAMBIT software
Overflow weir region 12 and the overflow region 13 of vertical and top is connected to overflow weir region 12 tetragonal body, the overflow weir area
The weir crest in domain 12 is level；The connected component in overflow weir region 12 and overflow region 13 is interface 6；
The overflow weir region 12 includes interface 6 and the import 1 for being located at the four directions body region front and rear sides face, respectively position
In the overflow weir region left side 2 of left and right sides and overflow weir region right side 3 and positioned at the overflow weir area of upper and lower end face
Domain top surface 4 and weir crest 5；The overflow region 13 includes being located on front side of the overflow region in the four directions body region front and rear sides face
Face 8, interface 6 and the weir body 7 positioned at 6 lower section of interface, are located at overflow region left side 9, the water of left and right sides
Tongue region domain right side 10 and positioned at upper and lower end faces overflow region top surface 14 and outlet 11.
The overflow weir region 12 may be configured as broad-crested weir, practical weir or sharp-crested weir, originally be embodied as broad-crested weir.
Weir crest 5 is set as horizontal, smooth face or line translate straight up using the face or line as generatrix or bus
Region is set as overflow weir region 12.
Preferably, the weir body 7 is set as vertical, smooth face, and the weir body 7 and weir crest 5 are wide.
Preferably, overflow region 13 is cuboid, which is set as bottom as side, with scour hole using weir body 7
Face.
The specific size in the overflow weir region 12 and overflow region 13 can be according to the down stream topography environment of practical study
It is adjusted and sets.
Illustrate in conjunction with Fig. 3, in the present embodiment, the overflow weir region 12 is set as broad-crested weir, and the weir crest 14 is set as
Horizontal, smooth face, the weir crest width B are set as 2.0 m, can be arranged according to the actual situation.
The 7 width F of weir body is set as 2.0 m, height C is set as 0.6 m.
The 12 length A of overflow weir region is set as calculating when the value setting of 0.5m, height D according to greater than weir formula
Value to H is set, and is highly 0.01 m in the present embodiment, and 0.01m is greater than the value that H is calculated according to weir formula.
The weir formula are as follows:
Q is water flow, which is equal to the inlet flow magnitude set in step (2)；B is the width F of the weir weir Kuan Ji body 7；G is
Acceleration of gravity；H is the numerical value of weir head；M is weir flow coefficient, and h is the height C of weir body 7, according to
It can obtain.It can be with according to presetting overflow flow Q
Calculate H value, the value of further setting height D.
The 13 width F of overflow region is set as 2.0 m, the L value that length E is obtained according to following calculation formula is set as
0.1 m, height (C+D) are set as 0.61 m.
mFor weir flow coefficient；hFor weir body height, the height C, unit m of weir body 7 in the present invention are corresponded to；HFor weir head, according to
The numerical value H that weir formula above obtains after calculating is configured, unit m.
It is 0.1 m that 11 width F of the outlet, which are set as 2.0 m, length E,.
Preferably, setting outlet 11 is scour hole, is set as rectangular surfaces, the rectangular surfaces and weir body or weir crest are wide.Institute
Scour hole length E is stated to be no less thanL, calculation formula is as follows:
Wherein,M is weir flow coefficient；hFor weir body height, the height C, unit m of weir body 7 in the present invention are corresponded to；HFor water on weir
Head, unit m.
In the present embodiment, in order to can completely show the form of overflow, institute in default water flow underflow stream weir model
The length E of the height D and the overflow region 13 that state overflow weir region 12 are required to be calculated according to above-mentioned weir formula, keep away
The water flow of the size and import of exempting from overflow weir model mismatches.
Drafting establishes the overflow weir model then structural grid of subdivision, and Gridding length is set as 0.001 m, grid distribution
As shown in Figure 2.Too small then step (2) iterative calculation of Gridding length is difficult, it is difficult to which Data Convergence, Gridding length is too big, data
Accuracy.
The setting method of boundary condition of the present invention are as follows:
The import 1 is set as speed or fluid inlet；Overflow weir region left side 2, overflow weir region right side 3, weir
Top 5, weir body 7 are set as wall, overflow weir region top surface 4, overflow region leading flank 8, overflow region left side 9, overflow area
Domain right side 10 is set as pressure export, and the interface 6 is set as inside face.
The overflow weir region 12, overflow region 13 are set as fluid.
The import 1 is set as speed or fluid inlet, and scour hole is in outlet 11 and is set as pressure outlet, opposite pressure
Value is set as -10.0 ~ 0.0 Pa.
(2) establish plunging nappe iterative calculation model comprising establish Turbulent Equations, Two-phase flow's separation, primary condition and
Relaxation factor；
The plunging nappe iterates to calculate model and can realize in Computational fluid mechanics numerical simulation software, such as FLUENT,
The softwares such as FLOW-3D but these softwares are not limited to, the present embodiment carries out in FLUENT.
Preferably, the solver of plunging nappe iterative calculation model be set as based on pressure or density, speed
It is constant or non-constant for absolute velocity, fluidised form.
Preferably, the Turbulent Equations are turbulent flow k- ε model；Its governing equation group includes continuity equation, the equation of momentum
And energy equation, the energy equation includekEquation andεEquation,
The continuity equation is as follows:
The equation of momentum is as follows:
It is describedkEquation is as follows:
It is describedεEquation is as follows:
In the turbulent flow governing equation group,u i 、u j For the speed of fluid；PFor the pressure of fluid；νFor the kinematic viscosity of fluid,ν=ν 0 + ν t ,ν t For turbulent motion viscosity,ν t = C u (k 2/ε),C u = 0.0845；；k
For tubulence energy；α k = 1.39；S ij = ∂u i ⁄ ∂u j +∂u j ⁄ ∂u i ；εFor tubulence energy dissipative shock wave；α ε = 1.39；RIt isεEquation
An addition Item, represent mean strain rate pairεInfluence,,It is turbulent flow
The ratio of time scale and mean flow time scale,,It is the norm of strain rate tensor,,
It isRepresentative value in uniform shear flow,,；c 1= 1.42；c 2 = 1.68。
Preferably, the Two-phase flow's separation is set as Volume of Fluid model, and the number of phases is set as 2, and setting water is the
One phase, air are the second phase.
It optionally, is that inlet velocity or flow, water volume fraction are set as 0, sky by flow velocity when the primary condition is set
Gas fraction be set as 1, temperature setting be 298 ~ 300 K, turbulent fluctuation energy and disorderly kinetic energy dissipation rate according tokEquation andεEquation meter
It calculates, respectively 1.51 × 10-5 m2/s2With 1.32 × 10-5 m2/s3。
It is inlet velocity or flow by flow velocity when the primary condition is set, which is in step (1), and weir flow is public
Flow Q value in formula can obtain flow speed value by the reduction formula of water flow and flow velocity.
The conversion relation of water flow and flow velocity is as follows:
Cause are as follows:,
Therefore:
Wherein, m is weir flow coefficient,；B is that weir is wide；G is
Acceleration of gravity；H is weir head；H is weir body height, the height of weir body 7 in the corresponding present invention.
Optionally, when the relaxation factor is arranged, by pressure, density, physical strength, momentum, turbulent fluctuation energy, turbulent fluctuation dissipative shock wave, disorderly
Flow viscosity, it is 0.0 ~ 0.3,0.0 ~ 1.0,0.0 ~ 1.0,0.0 ~ 0.7,0.0 ~ 0.8,0.0 ~ 0.8,0.0 ~ 1.0 that value, which is set gradually,.
Preferably, 0.3,0.8,0.8,0.7,0.8,0.8,0.5.
It carries out the plunging nappe iterative calculation model after condition initialization to calculate, time step is set as 0.001 s, changes
Generation number is set as 200,000 times.
(3) data file that step (2) obtains is led in TECPLOT, establishes numerical simulation result processing model, packet
Include setting color bar parameter, water volume fraction and two-phase display parameters.
The numerical simulation result processing model realizes that the color bar parameter is set in PaintShop TECPLOT
It is set to 0.0 ~ 1.0, color bar number is set as 2.0 ~ 40.0.
The water volume fraction is set as 0.1 ~ 1.0, and the two-phase display parameters are set as water and air.The present embodiment
In, the color bar parameter is set as 1.0, and the color bar number is set as 20, and the water volume fraction is set as 0.9, described
Two-phase display parameters are set as water and air.
Fig. 4-12 is respectively that the value of different flow in primary condition, corresponding different overflow state diagram is arranged in step (2)
Picture, by flow velocity according to the following formula it can be concluded that the water flow entered.The conversion relation of water flow and flow velocity is as follows:
Cause are as follows:,
Therefore:
Wherein, m is weir flow coefficient,；B is that weir is wide；G is
Acceleration of gravity；H is weir head；H is weir body height, the height of weir body 7 in the corresponding present invention.
The present invention is 0.00150 m in discharge per unit width Q3/s、0.00155 m3/s、0.00156 m3/s、0.00157 m3/
s、0.00158 m3/s、0.00159 m3/s、0.00160 m3/s、0.00170 m3/ s and 0.00200 m3Plunging nappe when/s
State diagram specifically, in Fig. 4, is in discharge per unit width Q it can be seen from the figure that overflow thickness becomes larger with the increase of rate of water added Q
0.00150 m3When/s, overflow forms moisture film, the atomization of overflow bottom end not successfully.It is 0.00155 in discharge per unit width Q in Fig. 5
m3It when/s, thickens compared with Fig. 4 overflow, but there are still a small amount of atomizating phenomenons for end.In Fig. 6, under the flow, molding has just been formed
Overflow, end is not atomized just, and overflow bottom end is a point.In Fig. 7, under the flow, complete overflow is formd,
Moisture film is complete, and end is without atomization.Fig. 8-Figure 11 forms complete overflow, and moisture film is complete, and end is without atomization, and with water flow
The increase of amount, moisture film are more and more thicker.In Figure 12, in 0.00200 m3/ s makes, and water film thickness is thicker, and reflection water flow is excessive,
There is waste and surplus in water resource, need to adjust water flow.
The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention.
Various modifications to these embodiments will be readily apparent to those skilled in the art, as defined herein
General Principle can be realized in other embodiments without departing from the spirit or scope of the present invention.Therefore, of the invention
It is not intended to be limited to the embodiments shown herein, and is to fit to and the principles and novel features disclosed herein phase one
The widest scope of cause.
Claims (10)
1. a kind of method of numerical simulation plunging nappe, it is characterised in that: itself the following steps are included:
(1) overflow weir model and then the structural grid of subdivision are established and boundary condition is set；
(2) plunging nappe iterative calculation model is established comprising establish Turbulent Equations, Two-phase flow's separation, primary condition and relaxation
The factor；
(3) numerical simulation result processing model is established comprising setting color bar parameter, water volume fraction and two-phase display ginseng
Number.
2. a kind of method of numerical simulation plunging nappe according to claim 1, it is characterised in that: described in step (1)
Overflow weir model includes the overflow weir region (12) of tetragonal body and the four directions that vertical and top is connected to overflow weir region (12)
The overflow region (13) of body, the weir crest of the overflow weir region (12) are level；Overflow weir region (12) and overflow region (13)
Connected component be interface (6)；
The overflow weir region (12) includes interface (6) and the import (1) for being located at the four directions body region front and rear sides face,
Be located at left and right sides overflow weir region left side (2) and overflow weir region right side (3) and be located at upper and lower end face
Overflow weir region top surface (4) and weir crest (5)；The overflow region (13) includes being located at the four directions body region front and rear sides
The overflow region leading flank (8) and interface (6) in face, the weir body (7) being located at below interface (6), are located at left and right two
Overflow region left side (9), overflow region right side (10) and the overflow region top surface positioned at upper and lower end faces of side
(14) and (11) are exported.
3. a kind of method of numerical simulation plunging nappe according to claim 2, it is characterised in that: in step (1), boundary
The setting method of condition are as follows:
The import (1) is set as flow velocity entrance or traffic ingress；Overflow weir region left side (2), overflow weir region are right
Side (3), weir crest (5), weir body (7) are set as wall, overflow weir region top surface (4), overflow region leading flank (8), overflow
Region left side (9), overflow region right side (10) are set as pressure export, and the interface (6) is set as inside face.
4. a kind of method of numerical simulation plunging nappe according to claim 2, it is characterised in that: the overflow weir region
(12) value of height (D) is greater than the value that H is calculated according to weir formula, the weir formula are as follows:
,
Q is water flow；B is the width (F) of the weir weir Kuan Ji body (7)；G is acceleration of gravity；H is weir head；M is weir flow system
Number, h are the height (C) of weir body (7),
H value, the value of further setting height D can be calculated according to presetting overflow flow Q；
The length (E) of the overflow region (13) is that the value setting of L is obtained according to following calculation formula,
mFor weir flow coefficient；H is the height (C) of weir body (7)；HFor weir head, can be calculated according to presetting overflow flow Q
H value.
5. a kind of method of numerical simulation plunging nappe according to claim 1, it is characterised in that: described in step (2)
Relaxation factor includes pressure, density, physical strength, momentum, turbulent fluctuation energy, turbulent fluctuation dissipative shock wave, turbulent viscosity, and value sets gradually as 0.0 ~
0.3、0.0~1.0、0.0~1.0、0.0~0.7、0.0~0.8、0.0~0.8、0.0~1.0。
6. a kind of method of numerical simulation plunging nappe according to claim 1, it is characterised in that: described in step (2)
Turbulent Equations are turbulent flow k- ε model；The Two-phase flow's separation be Volume of Fluid model or Mixture model or
Eulerian model, and it is arranged that water is the first phase, air is the second phase.
7. a kind of method of numerical simulation plunging nappe according to claim 1, it is characterised in that: described in step (2)
Primary condition is set as flow velocity being set as 1 flow velocity of import or flow, water volume fraction are set as 0, volume of air score and are set as
1, temperature setting be 298 ~ 300 K, turbulent fluctuation energy and disorderly kinetic energy dissipation rate according tokEquation andεEquation calculation.
8. a kind of method of numerical simulation plunging nappe according to claim 1, it is characterised in that: described in step (3)
Color bar parameter is set as 0.0 ~ 1.0, and color bar number is set as 2.0 ~ 40.0；
In step (3), the water volume fraction is set as 0.1 ~ 1.0, and the two-phase display parameters are set as water and air.
9. a kind of method of numerical simulation plunging nappe according to claim 1, it is characterised in that:
It is established in step (1) and imitates the overflow weir model that plunging nappe generates topography, it is structural to carry out subdivision after drafting and to it
Grid and the speed import that overflow is set；
Step (2) carries out space integral to each mesh point in step (1), and the flow velocity or flow of the import of overflow speed is arranged, into
Row iteration calculates；
Step (3) exports the result after step (2) iterative calculation convergence by image processing software, and it is default to obtain step (2)
Overflow form under flow velocity or flow.
10. a kind of method of numerical simulation plunging nappe according to claim 1, it is characterised in that: overflowing in step (1)
Stream weir model carries out in computer modeling software；The overflow weir model is imported into hydrodynamics numerical value after the completion of modeling and calculates mould
In quasi- software, plunging nappe iterative calculation is carried out, imports calculated result in PaintShop after stable convergence, adjusts numerical value
Result or dynamic effect are exported after the display effect of analog result.
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