Af31231237

SUHARJOKO, MOHAMMAD BISRI, RISPININGTATI, MUHAMMAD RUSLIN ANWAR / International
Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 3, Issue 1, January -February 2013, pp.231-237
Modelling Of Groyne Placement On The River Bend Based On
Sedimentation Analysis Using Numerical Simulation Approach
By Finite Difference Method
SUHARJOKO1, MOHAMMAD BISRI2, RISPININGTATI3, MUHAMMAD RUSLIN
ANWAR3
1
Doctoral Student At Master And Doctoral Program, Faculty Of Engineering, Brawijaya Unversity
And Lecturer At Civil Engineering And Planing Departement, Its, Surabaya,
2
professor At Civil Engineering Program, Faculty Of Engineering Science, Brawijaya University, Malang,
3
associate Professor At Civil Engineering Program, Faculty Of Engineering, Brawijaya University. Malang,
(Indonesia)

ABSTRACT
Modelling of groyne placement on the direction of flow (Louvre Groyne). Effectively,
riverbend based on sedimentation analysis having overcompensation is possible so that the deposition
a goal to development the good placement of height resulting from the constriction scour is
groyne to be considered of the sedimentation minimized and the frequency of occurrence and
accumulation volume on groyne field. To solved size of undepths is minimized. The sheltering effect
Modelling groyne placement would be simulation of the flow through the opening and the Island /
many case of groyne placement using lengthening of the groyne head itself turn the
mathematical modeling approach by finite sediment balance in the groyne fields from net-
different method. erosion to net-deposition, thus minimizing the
This research plant to simulation for the sediment load on the fairway during emerged state.
450 cases, that were combinations of various the Because of this, it is expected that maintenance
groyne position, various the groyne length, dredging can be minimized importantly. Fang,
various of the flow velocities, various of the radius (2005) [10], To improved of bend flow sediment
bend and various of the suspended load transport model has been developed by taking the
concentrations. From the data simulation influence of secondary current vertical velocity on
outcome, can be solved by regression analysis to vertical sediment concentration distribution into
obtain suitability coefficients Cvol.. account. But existing vertical velocity profiles of
secondary current and vertical sediment
Keyword : groyne placement, riverbend, concentration profiles in river bends are hardly
sedimentation analysis, mathematical modeling. available, further experiment study is necessary for
improving bend flow sediment transport models.
I. INTRODUCTIONS Duan 2006 [6], developed applications of
On the issues of concerning the groyne numerical hydrodynamics modeling two
placement, has been studied as follows; Suharjoko dimensional depth averaged to simulate suspended
1999 [1] and (2001) [2], has analyzed and reviewed sediment at the confluence of the rivers to get an
groyne has carried out to get changes conduct of flow illustrated of the sediment concentration
pattern and the best distance between groynes distribution around groyne. Zhang (2007) [7], this
impermeable using Computational hydrodinamics study investigates the flow and process of riverbed
simulations on a straight channel. The results of the change at a river rehabilitation projects by using
analysis was obtained relationship between the physical model and mathematical model. Prohaska
Froude number (Fr.) with long of embankment (2007) [5], results showed that conservative
protected and other parameters the results can be methods to determine erosion and to control
used to shown the best distance between the groyne. erosion around krib. The analysis gives the
Jungseok, 2005 [3], that research has carried out the effective value of the critical erosion shear stress to
distance between groyne used Numerical Modeling be smaller than the average value of the assent
to single permeability Groyne on rectangular channel shear stress. Susceptibility of erosion sediment to
(CFD) Flow-3D Software. While Heereveld (2006) contaminated pollutants is difficult to predict of the
[4], built the groyne river with consider the time physical processes because its had complex
contradictive assertions such as the reduction of the influence, chemistry and biology, as well as the
riverbed flow velocities and an increase fairway on lack of information. Armanini, 2010 [8], doing
the the top. At the extremities of the main channel, analysis experiment results of research with
the aforementioned bed level increase is expected to physical models in problems of scouring and
be larger, but this will be countered through the deposits around groyne. Formation of the groyne
Island and lengthening of the groyne head in the

231 | P a g e

shown clearly the influence of processes Improved a- process is the quantified level of agreement
gradations between the river groyne. between experimental data and model prediction,
The research mentioned has been applied to as well as the predictive accuracy of the model.
simulate the currents flow pattern around groyne and
to get shown the distribution of sedimentation B. Developing Mathematical Model and
concentration included concentration of Vortex-flow verification & validation
around the groyne. But there has been no research to Developing the Conceptual Model involves
get the good placement of groyne that considered of identifying the computational objective, the
sedimentation accumulation volume on groyne field required level of agreement between the
using numerical simulation approach by depth experiment and simulation outcomes, the domain
averaged two-dimensional fined difference flow of interest, all important physical processes and
models. assumptions, the failure mode of interest, and the
validation metrics (quantities to be measured and
II. METHOD the basis for comparison). Once the Conceptual
A. Modelling groyne placement. Model is developed, the modeler constructs the
A modelling of groyne placement on the Mathematical Model, and the experimenter designs
riverbend based on sedimentation analysis, having a the Validation Experiment. The Mathematical
goal to development the good placement of groyne Model is a set of mathematical equations intended
that were to be considered of the volume to describe physical reality. The Mathematical
sedimentation accumulation on groyne field. To Model of hydrodinamics includes the mass
solved Modelling groyne placement would be conservation equation and momentum equations,
simulation many case of groyne placement using the sedimentation equations and temporal domain,
mathematical modeling. To development the initial and boundary conditions, the constitutive
mathematical/numerical models were used, these equations, and the relationships describing the
models needed process verification and validation model’s uncertainty. (Thacker Ben H., 2004,[11])
(V&V). The expected outcome of the model V&V More detail can be seen in figure 1 follow.

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C. Conservation Equations 2
1  36  36
Mathematical Model of hydrodinamics includes the ws  
 d   7.5( p  1) gdn 

mass conservation equations and momentum 2.8  n  dn
equations. The Conservation Equations called
Continuity equations was based on the conservation
Where, dn is Normal diameter, p is
of mass concept, Abbort, 1979 [12]. The continuity
sediment concentration and g is sediment
equations two dimension horizontal be represented
concentration.
as follow
  (hu)  (hv)
  0 The Migniot (1989) on Signh 2005 [13] formula is
t x y used to calculate the cohesive sediment settling
Where,  = water level fluctuations velocity:
h = Water depth, 250
d = still water depth (constant), wsc  ws
u = mean velocity in the x direction, d2
v = mean velocity in the y direction. Where : wsc = settling velocitys of cohesive
sediment flocs
D. Momentum equations ws = settling velocitys of single
The Momentum equations was constructed based on cohesive sediment Stoke Law is
the Newton II low [12], The momentum equations used to calculate the single
two dimension horizontal be represented as follow. cohesive sediment particle
u u u  g gd 2
u v  g  2 u u 2  v 2   2 u , s  (s   )
t x y x C z 18 
v v v  g G. Settlement of Suspended sediments
 u  v  g  v u 2  v 2   2 v ,
t x y y C z 2 Dyer 1986 on widagdo 1998 [15], introduce the
equation to calculate the rateo f setled sediment as
Where,  2       .
2 2
 2
 x  follow,
 y 2 
 dm   
Cz = Chezy Coefficient  pws 1  
  
g = gravitation accelerations dt  c 
Where m is the mass sediment settle to be
E. Equation of suspended sediment dispersed deposited, p is the sediment, , c are the shear
Wexier (1992) on Signh 2005 [13] developed an stress and critical shear stress for settlement
analytical solution for two-dimensional advection- respectively.
diffusion equation including source-sink term.   RS , for wide channels hydraulic radius R can
Diffusion coefficients and velocity profile were taken be taken as the depth of flow h.
constant spatially. He developed an analytical Indri,s formula on Signh 2005 [13] proposed the
solution for the following form of the following formula for critical shear stress for
advectiondiffusion equation, which can be derived by incipient motion for sediment particle are:
assuming unit depth and spatially constant diffusion
coefficients and velocity profile.

Where c = Critical shear stress in gm/m2, d = mean
diameter of sediment in mm, M = uniformity
coefficient

H. Bed Elevation Change
As described in the equation 3.54 the bed elevation
change due to sediment erosion and deposition can
be represented by the following equation [13]:

F. Settling velocity Writing this equation in discrete form for
Liu 2001 [14], The settling velocity of the sphere of incorporating in the model for calculating the bed
suspended sediment ws give elevation change after each time step,

233 | P a g e

The parameters were mentioned ;
a. Morphology Factor
B : River with ,
R : Radius Bend,
β : Angle Bend
b. Hydrology and Hydrometry factor
where is the fractional change in bed elevation u : Flow Velocyties
at the end of nth time step due to the kth fraction of h : Water depth
sediment. The total bed elevation change after each  : density of water
time step can be calculated by summing all the  : Viscocty, degree of fluidity in a fluid
fractional bed changes due to all sediment fractions: c. Suspended Load
p : sediment concentration ,
I. Regression Analysis d50 : is mean diameter of soil grain size,
Regression analysis can be provide from the  : specific grafity of soil sediment,
relationship between variables from one or more free Vol : Sedimentation accumulation
variables to get approximate predictions ,Triatmojo d. Groyne placement factor
2001, [16] [17]. The purpose of regression analysis is : Position of Groyne,
to obtain a function as a forecast. L : Lengt of Groyne,
A linear regression equation with one independent  : angle of Groyne placement, in this
variable (x)was,
recearch  =900
y  a0  a1 x
Or nonlinear/exponential regression analysis as Suharjoko (2001) [2], done research on directional
follows groyne with different angles on the straight
channel, resulting that in a groyne was placed
Ei  aebxi perpendicular to the flow direction is the best.
The exponential regression equation can solved to the Based on this reference, further research was
linear regression equation as follows. restricted the groyne was placed on perpendicular
ln(Ei ) = ln(a) + bxi ln(e) to the flow direction (angle  = 900 ).
From the explanation above, the parameters that
III. RESULTS AND DISCUSSION effected to sedimentation accumulations (Vol), can
A. The Relationship of SEDIMENTATION be expressed mathematically as follows ;
ACCUMULATION with the GROYNE Vol = f ( B, R, β,  , u, h, , p, d50, , , L,t) various of
PLAYCEMENT rroyne placement.
There is a relationship that influence C. Non-Dimentional Parameters
between the groyne placement with the sedimentation To get the parameters relationships of
accumulation on the groyne field. Be expected that a sedimentation accumulation on the groyne field be
good groyne placement will be given if volume the come a generaly formulation, be solved with non-
sedimentation accumulation is bigger. The groyne dimensional analysis by Stepwise Method,
placement, angle bend of the river and radius of the Yuwono 1994 [18]. That is to get how the
river bends are variables which have great impact to parameters relationships be come no-dimensional
caused the sedimentation accumulation. by elimination of dimension stage by stage. In the
Table 1 below were shown a solved non-
B. The relationship of Parameters dimensional analysis by Stepwise method.
The relationship of parameters there were caused to
changes of sedimentation deposition accumulation on From Table 1 above, non-dimensional value be
groyne field shown in figure 1 are; expressed as follows.
 Vol B R D d  h gh ut 
   3 , , , , 50 , , , 2 , tg , p, 
 h h h h h u  u
 h 
To be expected that Groyne placement have an
impact of sedimentation accumulations on the
groyne field was solved to compile an equations
formulation from the non-dimensional value be
expressed as a model that reflected the relationship
of sedimentation accumulations with the
parameters to have an impact, as follows,

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Vol h   ut position at the beginning of the arc of the
p tg (  ) Fr , can be riverbend, Position 2 is the groyne position at ¼
BRL d 50 u h h upper of the arc of riverbend and Position 3 is the
simplified groyne position at the middle of the arc of
p h riverbend, More details can be seen in Figure 3
 BRL 
Vol
tg (  ) Fr below.
t d 50 
where : For all case research planned simulation, there were
 (Vol) sedimentation accumulation 450 times simulations, that were combinations of
 p is the suspended load concentration various the groyne position, various the groyne
 Fr. is Froude Number thats equal length, various of the flow velocities, various of the
radius bend and various of the suspended load
Fr  u
gh concentrations. To explained the research of Model
groyne placement on the riverbend based of
Afterwards to be correction inequalities sedimentation analysis, more detail are shown in
formulations above be come an equations, will be Figure 4.
done to obtain suitability coefficients Cvol.. The value From the data outcome of the 450 times simulation,
of this suitability coefficient can be generated from can be solved using regression analysis to gotten
the data analysis from result of the simulation to the suitability coefficient (Cvol) of relationship
many variety and combination of other parameters of sedimentation accumulation with parameters that’s
groyne. effected,.

By getting the suitability coefficient of IV. CONCLUSION
sedimentation accumulation Cvol., the relationships This research planed to simulation for the
with parameters that effect mentioned above, 450 times, that were combinations of various the
becomes a following equation. groyne position, various the groyne length, various
of the flow velocities, various of the radius bend
p h
Vol
t
 Cvol BRL 
d50 
tg (  ) Fr m 3

/ dt , if and various of the suspended load concentrations.
From the data simulation outcome, can be solved
to be considered in the different time, so this equation by regression analysis to obtain suitability
became the differensial equation as follow, coefficients Cvol.. That is the suitability coefficient
be edd to the relationship of sedimentation
p h
d (Vol )
dt
 Cvol BRL 
d50 
tg (  ) Fr m 3
/ dt  accumulation with the parameters that’s effected on
groyne placement models.
This research planned simulation concerned to three
variations of the groyne position; Position 1 is groyne
Tabel 1 ; A solved non-dimensi analisis by Stepwise method.
Vol B R D  u h  d 50  g t p β
 M/L2) L
3
L L L M/L
2
L/T L M/LT L M/L3 L/T
2
T 1 1
Vol B R D / u h / d 50 / g t p tg β
u  L/T) L3 L L L 1 L/T L L/T L L -1 L/T2 L 1 1
Vol B R D u/u h / u d 50 / g/u 2 ut p tg β
3 -1 -1
h(L) L L L L 1 L 1 L L L 1 1 1
Vol/h 3
B/h R/h D/h / u d 50 /h h / gh/u 2
ut/h p tg β

D
D
L

L

L

D
u


u u



B

B

B

GROYNE GROYNE
Sedimentation Sedimentation
Accumulation Accumulation GROYNE
Sedimentation
Accumulation

R R R

Position 1. : Groyne at the upstream Position 2. : Groyne at the 1/4 Position 3. : Groyne at the central art
art of riverbend upstream art of riverbend of riverbend

Figure 3 : Variaos of groyne positions on the riverbend.

235 | P a g e

Reference Coonrod, and Won-Sik Ahn,
1 Suharjoko, Study on Numerical Modeling of NUMERICAL MODELING STUDY
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Yogyakatra, 1999. Murray, M. G. 162 , 2005.
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Two-Dimentional Horizontal Flow on FOR THE FUTURE innovative groyne
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the River Straight, Recearches Report, EU Habitats Directive. 2006.
Departemen of Recearch and Public 5 Prohaska Sandra, Thomas Jancke,
Official, Institute of Technologie Sepuluh Bernhard Westrich, MODEL BASED
Nopember, Surabaya, 2001. ESTIMATION OF SEDIMENT
3 Jungseok Ho, Hong Koo Yeo, Julie EROSION IN GROYNE FIELDS

START

River With B = 20 m, Slope So
Angle Bend ß = 60 o
g, , , d 50 , , Cr, dx, dy, dt

T = time simulations
jt = T/dt for t=1 to jt

Groyne Position: Pos(k) For k=1 to 3
Posisi 1, Posisi 2, Posisi 3

length of Groyne various: LPB(l)
For l=1 to 3
L/B=1/5; L/B=1/3; L/B=1/2

velocyties various: u(m)
u(1)=0.6; u(2)=0.8; u(3)=1.0; For m=1 to 5
u(4)=1.2; u(5)=1.4 m/dt

Radius Bend : R(n)
For n=1 to 2
R(1)=30 m, R(2)=40 m.

Suspended Load : p(o)
p(1)=0.001 %, p(2)=0.005 %, For o=1 to 5
p(3)=0.01%, p(4)=0.03%, p(5)=0.05%.

Numerical Modelling of RUNNING SIMULATION USING
NUMERCAL MODELLING
Hydrodinamics and
APPROACH BY FINITE
Sedimentation
DIFFERENCE METHOD

(Regression ANALYSIS ) Outcames Parameter;
450 data
to found the corrected of sedimentation
formulation accumulation, flow pattern,
flow perspective

Coefficient Corrected
Next : o
CVol Next : n
Next : m
Next : l
Next : k

The Relationship of SEDIMENTATION Next : t
ACCUMULATION with the GROYNE PLAYCEMENT

p h
d (Vol )
dt
 Cvol BRL 
d 50 
tg (  ) Fr m 3
/ dt  End

Figure 4 : Researches Method

236 | P a g e

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