# Influence of Rack Slope and Approaching Conditions in Bottom Intake Systems

^{*}

## Abstract

**:**

## 1. Introduction

_{1}, and the total area, b

_{1}+ b

_{w}, where b

_{w}is the bar width), and the approaching flow conditions such as the initial flow depth, h

_{1}, or the longitudinal rack slope, tanθ.

_{q}

_{0}, obtained with null approaching velocity, the influence of the first two factors can be observed (Noseda [8], Brunella et al. [9], Righetti and Lanzoni [10]).

_{c}, in function of the specific approaching flow and the Froude number at the beginning of the rack, q

_{1}/F

_{r}

_{1}. Formulae consider the void ratio m = 0.60, and a longitudinal slope of 20%. Expressions assume the simplification of horizontal energy level or constant specific energy, not considering the possible energy losses along the rack. Differences between formulae are mainly due to the shape of the bars. For the T-shaped case and the prismatic plane bars, the dimensionless wetted rack length is 3.20–3.70 (Frank [13], Drobir [4], Bouvard and Kunztmann [14], Krochin [3], Noseda [8]). However, in circular or prismatic rounded bars the dimensionless wetted rack length is 1.98–2.87 (Brunella et al. [9], Righetti and Lanzoni [10], Vargas [15]).

_{2}, and the maximum wetted length in the space between bars, L

_{1}. The length proposed by the free overfall, in the case of a horizontal channel that ends in a brink (around 1.4) is also presented (Henderson [17]). Krochin [3] introduces the f factor to consider the percentage of rack that is occluded (see Appendix A). In Figure 1 no occlusion has been considered (f = 0).

_{qH}is the discharge coefficient considering the energy height in the orifice equation, H

_{0}the energy height at the beginning of the rack, x the longitudinal coordinate in the rack plane, θ the angle between the bottom rack and the horizontal, m the void ratio, h the flow depth along the rack, and g the gravitational acceleration.

_{1}, at the inlet section and the approaching flow, q

_{1}. With these assumptions, Brunella et al. [9] proposed an adjustment to calculate the flow profile along the bottom rack for longitudinal slopes steeper than 19° (34.4%).

_{y,slit}and P

_{slit}are the perpendicular component of the velocity vector and the static pressure in the slit, respectively (Figure 2c).

_{slit}, and using a contraction coefficient, C

_{c}, to consider the effective area:

## 2. Materials and Methods

#### 2.1. Laboratory Flume

_{w}is the width of the bars. This table includes the flow characteristics of the 60 tests carried out, such as: flow depth, h

_{1}, energy head at the beginning of the rack, H

_{0}, Froude number at the beginning of the rack, F

_{r}

_{1}, and ratio of the flow rejected at the end of the 0.90 m length rack, q

_{2}, to the approaching flow, q

_{1}. The ratio of q

_{2}/q

_{1}below 4% usually corresponds to the flow rejected through the top part of the planar bars. The Froude numbers at the beginning of the rack grow from horizontal to 33% rack slopes, adopting values from 1.28 to 2.08. The range F

_{r}

_{1}obtained in the tests is representative of the flow conditions found in intermediate and steep slope rivers. Vargas [15] and Drobir [16] are examples of direct applications of the Froude modeling in two steep slope rivers, where the Froude numbers agree with the range studied.

_{c}, is presented at a cross section located x = −0.50 m upstream of the rack. As values are close to the unit, this zone is where the flow profile starts to decrease.

#### 2.2. Instruments

^{®}(Thielicke and Stamhuis [29]). In each test 80,000 images were recorded. The velocity values were averaged. The longitudinal velocity fluctuation turbulence intensity was around 0.04–0.15, increasing from the bottom.

_{t}

_{,β}the total pressure (dynamic and static) registered by the Pitot tube in the β direction, ΔP the deviation of the pressure from hydrostatic, U

_{β}the velocity component in the β direction, and y the perpendicular coordinate.

#### 2.3. Numerical Simulations

_{i}defines the coordinate directions (i = 1 to 3 for x, y, z directions, respectively), t the time, ρ the flow density, p the pressure, U the velocity vector, ${u}_{i}^{\prime}$ the turbulent velocity, S

_{ij}the mean strain-rate tensor, μ the molecular viscosity, and $\mathsf{\rho}\overline{{u}_{i}^{\prime}{u}_{j}^{\prime}}$ is the Reynolds stress (ANSYS Inc. [30]).

#### 2.4. Experimental and Numerical Campaign

_{1}= 53.80; 77.00; 114.60 and 155.40 L/s/m for racks A, B, and C (m = 0.16, 0.22, and 0.28, respectively); and five longitudinal rack slopes: 0, 10%, 20%, 30%, and 33%. This entails 20 tests per rack. In each case, the free-surface flow profile and the flow derived per unit of length were measured. The total wetted rack length and the rejected flow at the end of the rack were also analyzed. Table 2 also shows the range of Froude number, F

_{r}

_{1}, total head H

_{0}, and flow depth measured at the beginning of the rack in the experiments.

_{1}= 77.00; 114.60 and 138.80 L/s/m).

## 3. Results and Discussion

#### 3.1. Free Surface Flow Profile

_{q}

_{0}, was measured in a laboratory with a rack length of 0.30 m and placing a vertical wall at the end of the rack. Further details of how to measure the static discharge coefficient can be found in [8,9]. Therefore, the kinetic energy becomes potential and the Froude number of the approaching flow, F

_{r}

_{1}, tends to 0. Figure 6a shows the values obtained for several approaching flows as a function of the void ratio. Figure 6b compares the averaged values of the static discharge coefficient, C

_{q}

_{0}, calculated for each void ratio using T-shaped bars with those obtained by Garot [11], Noseda [8], Brunella et al. [9], and Righetti and Lanzoni [10] testing different shaped bars. In accordance with the results, an exponential adjustment of the C

_{q}

_{0}value is proposed as a function of the rack shape:

_{c}value by the (1 + tanθ) factor, data adjust to a single curve over the rack.

#### 3.2. Wetted Rack Length

_{1}, measured in the laboratory adjusts to the values that Brunella et al. [9] considered as wetted length (see Figure 5 and Figure 7). However, the wetted rack length for T-shaped bars, L

_{2}, measured over the rack presents the influence of the rack slope.

_{0}= H

_{min}, while C

_{qh}is the average of the discharge coefficient values along the rack (calculated as 1.3 times the static discharge coefficient, C

_{q}

_{0}, with a good approximation).

#### 3.3. Velocity and Pressure Fields over the Rack

_{x}, while the right plots refer to the perpendicular velocity component, U

_{y}. Values are compared in several sections along the rack (x = 0.00, 0.05, 0.10, and 0.20 m). The maximum differences in the longitudinal velocity component, U

_{x}, are around 0.10 m/s, (<7%). For the perpendicular velocity component, U

_{y}, differences are around 0.025 m/s, (<5%).

_{1}= 114.60 L/s/m, and slopes of 0% and 30%. The energy level starts with values over the minimum energy (water flow depths smaller than the critical depth). For the 0% slope, the energy level remains horizontal. However, the dissipation through the rack is around 0.10 m/m for the 30% rack slope.

_{i}is the module of the velocity vector located in the position i, U the mean velocity vector in the section analyzed, q the flow along the rack in the x coordinate, and P the static pressure in the y coordinate.

_{t,}

_{β}, and using the velocity field measured with the PIV system, the static pressure in the flow is calculated from Equation (4). Figure 13 shows the values for the approaching flow q

_{1}= 114.60 L/s/m, horizontal slope, and several longitudinal coordinates. The static pressure measured with Pitot tubes inclined 0° and 22° approximates to the numerically simulated values.

#### 3.4. Discharge Coefficient

_{0}= H

_{min}. The C

_{qH}values are influenced by the void ratio and the slope. Lower values are obtained for the higher slopes and void ratios. In all the cases, the coefficient decreases as the flow moves along the rack. Figure 14 presents the C

_{qH}multiplied by the factor (1 + tanθ), which allows us to estimate a unique adjustment. Considering the results, an exponential equation is proposed to calculate the discharge coefficient along the rack, as a function of rack slope:

_{H}

_{0}at the beginning of the rack (see Appendix A).

_{1}= 155.40 L/s/m and horizontal slope.

_{1}= 155.40 L/s/m, T-shaped bars, m = 0.28, and 0 and 33% rack slopes. Laboratory data are compared with the values proposed by Noseda [8] for the discharge coefficient included in the Appendix A, and with the numerical resolution of the following equations:

_{qH}and the sine of the angle of the velocity vector seems clear.

_{qH}. From the velocity and pressure fields, the static pressure head in the slit may be obtained. A contraction coefficient has to be experimentally adjusted. If the horizontal energy level with initial value equal to minimum energy is considered, then an additional coefficient K needs to be introduced:

_{c}K ≈ 0.88.

## 4. Conclusions

_{qH}(x) has been proposed in Equation (17). Following Righetti and Lanzoni [10], the discharge coefficient has been compared with the sine of the angle of the velocity vector in the slit. The results show good agreement.

## Acknowledgments

## Author Contributions

## Conflicts of Interest

## Abbreviations

a | constant depending on the shape of bars in Equation (10); |

b_{1} | space between bars; |

b_{w} | bar width; |

C_{c} | contraction coefficient for effective flow area; |

C_{qH} | discharge coefficient for energy head; |

C_{qh} | discharge coefficient for flow depth; |

C_{q}_{0} | static discharge coefficient; |

f | percentage of occluded rack in Equation of Krochin [3] included in Appendix A; |

g | gravitational acceleration; |

H | energy head along the rack referred to the rack plane; |

H_{0} | energy head at the beginning of the rack referred to the rack plane; |

h_{c} | critical depth; |

h_{1}, h_{2} | flow depth at the beginning and end of the rack, respectively; |

i | longitudinal slope, tanθ; |

k_{1}, k_{2} | constants of wetted rack length formulations of Krochin [3] and Vargas [15] respectively included in Appendix A; |

L | wetted rack length; |

L_{1}, L_{2} | maximum wetted length over the bar and in the slit, respectively; |

m | void ratio; |

P | static pressure; |

p_{t,} _{β} | total pressure measured in Pitot tube tip in the direction of the axis with inclination β with the horizontal; |

p_{slit} | static pressure in the slit between two bars; |

q_{1} | specific approaching flow; |

q_{2} | specific flow at the end of the rack; |

U | mean velocity vector; |

U_{i} | module of the velocity vector located in the position i; |

U_{x}, U_{y} | component of the velocity vector in the longitudinal and perpendicular coordinate, respectively; |

U_{β} | component of velocity vector in the direction of the axe of inclination β; |

x | longitudinal coordinate; |

y | perpendicular coordinate; |

α | velocity coefficient of the energy equation; |

β | angle of inclination of the Pitot tube; |

ρ | density; |

θ | angle of the rack plane with the horizontal; and |

λ | pressure coefficient of the energy equation |

## Appendix A

References | Experimental Setup | Wetted Rack Length, L (m) |
---|---|---|

Noseda [8] | q_{1max} = 100 L/s; B = 0.50 m; 0.16 < m < 0.28; 0.57 < b _{1} < 1.17 cm; T-shaped bars; slopes: 0%–20% | $L=1.1848\frac{{H}_{0}}{{C}_{qh}m}$; ${C}_{qh}=\overline{{C}_{qh}\left(h\right)}$; ${C}_{qh}\left(h\right)=0.66{m}^{-0,16}{\left(\frac{h}{l}\right)}^{-0.13}$ |

Bouvard and Kuntzmann [14] | Information from Noseda [8] | $\begin{array}{l}L=\left\{\frac{1}{2{m}^{\prime}}\left[\left(j+\frac{1}{2{j}^{2}}\right)\mathrm{arcsin}\sqrt{\frac{j}{j+\left(1/2{j}^{2}\right)}}+3\sqrt{\frac{1}{2j}}\right]+\left(\frac{0.303}{{{m}^{\prime}}^{2}}+\frac{2{j}^{3}-3{j}^{2}+1}{4{j}^{2}}\right)tg\mathsf{\theta}\right\}{h}_{1}\mathrm{cos}\mathsf{\theta}\hfill \\ j=\frac{{h}_{1}}{{h}_{c}}\text{}=1;\text{}{m}^{\prime}={C}_{q0}m;\text{}{C}_{q0}=0.82\hfill \end{array}$ |

Frank [13] | Information from Noseda [8] | $L=2.561\frac{{q}_{1}}{\mathsf{\lambda}\sqrt{{h}_{0}}}$; $\mathsf{\lambda}=m{C}_{qh}\sqrt{2g\mathrm{cos}\mathsf{\theta}}$; ${C}_{qh}=\overline{{C}_{qh}{\left(h\right)}_{Noseda}}$ |

Krochin [3] | Information from Melik-Nubarov [24]; prismatic and flat bars. | $L={\left[\frac{0.313{q}_{1}}{{\left({C}_{qH}{k}_{1}\right)}^{\raisebox{1ex}{$3$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}}\right]}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}$; ${k}_{1}=\left(1-f\right)m$; ${C}_{qH}={C}_{0}-0.325\mathrm{tan}\mathsf{\theta}$; ${C}_{0}=0.50$ |

Drobir [4] | Information from Frank [13] and Bouvard and Kuntzmann [14] | $L=\frac{0846}{{C}_{qh}m{\mathrm{cos}}^{1/2}(\mathsf{\theta})\sqrt{x}}\sqrt[3]{{q}_{1}^{2}}$; $2\mathrm{cos}\mathsf{\theta}{x}^{3}-3{x}^{2}+1=0$; ${C}_{qh}=\overline{{C}_{qh}{\left(h\right)}_{Noseda}}$ |

Drobir et al. [16] | q_{1max} = 20 L/s; B = 0.50 m; m = 0.6; b _{1} = 1.50 cm; b_{w} = 1 cm; Circular bars; Slope: 0%–20% | $\begin{array}{l}{L}_{1}=0.9088{q}_{1}^{0.4993}\\ {L}_{2}=1.7205{q}_{1}^{0.4296}\end{array}$ L _{TIWAG} |

Brunella et al. [9] | q_{1max} = 100 L/s; B = 50 cm; circular bars Two setups: (a) b _{1} = 1.20 cm; b _{w} = 0.6 cm; m = 0.352 (b) b_{1} = 0.6 cm; b _{w} = 0.3 cm; m = 0.664; Slope: 0°–51° | $L=\frac{0.83{H}_{0}}{{C}_{q0}m}$; ${C}_{q0}=0.87$ |

Righetti and Lanzoni [10,39] | q_{1max} = 37.5 L/s; B = 25 cm; prismatic with rounded edge; m = 0.20; b _{1} = 0.50 cm; b_{w} = 2.00 cm | $\Delta Q={C}_{q0}mBL\sqrt{2g{H}_{0}}\left(\frac{a}{2}\frac{L}{H}{F}_{H0}+1\right){\left\{\mathrm{tanh}\left[{b}_{0}\left(\sqrt{2}-{F}_{H0}\right)\right]\right\}}^{{b}_{1}};$ ${F}_{{H}_{0}}=\frac{{U}_{0}}{\sqrt{g{H}_{0}}}$; $a=-0.1056$; ${b}_{0}=1.5$; ${b}_{1}=0.478$ |

Vargas [15] | q_{1max} = 40 L/s; B = 55.20 cm; circular bars slope: 0°–20°; Two setups: (a) m = 0.33; b _{1} = 0.50 cm; b_{w} = 1 cm; (b) m = 0.5; b _{1} = 1 cm; b_{w} = 1 cm | $L={k}_{2}\sqrt{\frac{2\mathrm{cos}\mathsf{\theta}{q}_{1}{}^{2}}{mg{h}_{1}}}$; ${k}_{2}=1.1$ |

Henderson [17] | - | Free overfall; $L=1.4{h}_{c}$ |

_{1}= h

_{c}; flow depth considered at the end of the rack, h

_{2}= 0; energy depth at the beginning of the rack, H

_{0}= H

_{min}, B = width of the channel.

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**Figure 1.**Dimensionless wetted rack lengths as a function of critical flow depth of approaching, h

_{c}, proposed in literature for racks with void ratio m = 0.60 and 20% of slope.

**Figure 2.**Bottom intake system: (

**a**) Top view of the rack; (

**b**) frontal view of the T-shaped bars; (

**c**) scheme of the flow over a bottom intake system.

**Figure 3.**Bottom intake system at the Hydraulic Laboratory of the Universidad Politécnica de Cartagena.

**Figure 4.**Flow profiles over the center of the bar with 20% rack slope as a function of the mesh size.

**Figure 5.**(

**a**) Dimensionless flow depth, h/h

_{c}, as a function of the slope; (

**b**) dimensionless values as a function of the void ratio.

**Figure 6.**(

**a**) Static discharge coefficient, C

_{q}

_{0}, for void ratios m = 0.16, 0.22, 0.28, and different approaching flows, q

_{1}; (

**b**) static discharge coefficient, C

_{q}

_{0}, from several authors with respect to the bar shape and void ratio adjusted by exponential functions.

**Figure 8.**Wetted rack length measured in lab and calculated: (

**a**) calculated with Equation (12); (

**b**) calculated with Equation (13).

**Figure 9.**Velocity field and streamlines measured with PIV and simulated with CFD for rack with m = 0.28, horizontal slope, and approaching flow q

_{1}= 77.00 L/s/m.

**Figure 10.**Longitudinal and perpendicular components of the velocity, U

_{x}(

**left**) and U

_{y}(

**right**) calculated with PIV and simulated with CFD.

**Figure 11.**Energy head for approaching flow, q

_{1}= 114.60 L/s/m: (

**a**) with horizontal slope; (

**b**) with 30% slope.

**Figure 12.**Velocity and pressure coefficients of the energy equation along the rack for horizontal slope and several approaching flows, q

_{1}: (

**a**) Velocity coefficient α; (

**b**) pressure coefficient λ.

**Figure 13.**Pressure distribution along the flow calculated from PIV and Pitot measurements and simulated with CFD. Comparison with theoretical values.

**Figure 15.**Flow profile and derived flow per unit length calculated and measured in the lab for slopes of 10% and 33%.

**Figure 16.**Discharge coefficient, C

_{qH}, calculated from Equation (1) with the energy head measured and the sine of the angle of velocity vector in the slit between two bars simulated with CFD.

**Figure 17.**Discharge coefficient, C

_{qH}, calculated from pressure field and Equation (20), compared with values calculated from Equation (1).

Author | Flow | Flume Width | Shape | Setting | Slope |
---|---|---|---|---|---|

Noseda [8] | q_{1max} = 100 L/s | B = 0.50 m | T-shaped | 0.16 < m < 0.28 0.57 < b _{1} < 1.17 cm | 0%–20% |

Brunella et al. [9] | q_{1max} = 100 L/s | B = 0.50 m | Circular | Two setups: (a) b _{1} = 0.60 or 0.30 cm; b _{w} = 1.20 or 0.60 cm; m = 0.352 (b) b _{1} = 1.80 or 0.90 cm; b _{w} = 1.20 or 0.60 cm; m = 0.664 | 0%–123% |

Righetti and Lanzoni [10] | q_{1max} = 37.5 L/s | B = 0.25 m | Prismatic with rounded edge | m = 0.20; b_{1} = 0.50 cm; b_{w} = 2.00 cm | <3.5% |

tanθ (-) | q_{1} (L/s/m) | Rack A (m = 0.16) (b _{1} = 0.0057 m; b_{w} = 0.03 m) | Rack B (m = 0.22) (b _{1} = 0.0085 m; b_{w} = 0.03 m) | Rack C (m = 0.28) (b _{1} = 0.0117 m; b_{w} = 0.03 m) | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|

h_{1} (m) | H_{0} (m) | F_{r}_{1} (-) | q_{2}/q_{1} (%) | h_{1} (m) | H_{0} (m) | F_{r}_{1} (-) | q_{2}/q_{1} (%) | h_{1} (m) | H_{0} (m) | F_{r}_{1} (-) | q_{2}/q_{1} (%) | ||

0 | 53.8 | 0.053 | 0.106 | 1.42 | 1.9 | 0.055 | 0.104 | 1.32 | 1.9 | 0.055 | 0.104 | 1.34 | 1.9 |

77.0 | 0.069 | 0.132 | 1.36 | 2.6 | 0.070 | 0.132 | 1.33 | 1.3 | 0.069 | 0.132 | 1.35 | 1.3 | |

114.6 | 0.090 | 0.163 | 1.36 | 4.4 | 0.091 | 0.162 | 1.33 | 1.7 | 0.089 | 0.164 | 1.38 | 0.9 | |

155.4 | 0.114 | 0.208 | 1.28 | 20.6 | 0.110 | 0.212 | 1.36 | 3.2 | 0.109 | 0.212 | 1.37 | 2.6 | |

0.10 | 53.8 | 0.049 | 0.111 | 1.59 | 1.9 | 0.048 | 0.112 | 1.64 | 1.9 | 0.048 | 0.112 | 1.63 | 1.9 |

77.0 | 0.062 | 0.141 | 1.61 | 3.9 | 0.063 | 0.140 | 1.57 | 1.3 | 0.061 | 0.142 | 1.62 | 1.3 | |

114.6 | 0.083 | 0.181 | 1.54 | 5.2 | 0.082 | 0.182 | 1.57 | 1.7 | 0.080 | 0.185 | 1.63 | 1.7 | |

155.4 | 0.102 | 0.221 | 1.53 | 21.2 | 0.100 | 0.224 | 1.58 | 3.9 | 0.100 | 0.223 | 1.56 | 3.2 | |

0.20 | 53.8 | 0.044 | 0.121 | 1.89 | 3.7 | 0.044 | 0.120 | 1.85 | 1.9 | 0.044 | 0.120 | 1.85 | 1.9 |

77.0 | 0.057 | 0.150 | 1.80 | 3.9 | 0.058 | 0.148 | 1.77 | 1.3 | 0.057 | 0.149 | 1.79 | 2.6 | |

114.6 | 0.076 | 0.191 | 1.73 | 6.1 | 0.077 | 0.191 | 1.73 | 2.6 | 0.076 | 0.191 | 1.73 | 2.6 | |

155.4 | 0.096 | 0.230 | 1.68 | 21.9 | 0.096 | 0.230 | 1.68 | 4.5 | 0.095 | 0.232 | 1.70 | 4.5 | |

0.30 | 53.8 | 0.042 | 0.126 | 2.00 | 3.7 | 0.041 | 0.127 | 2.04 | 1.9 | 0.042 | 0.126 | 2.00 | 3.7 |

77.0 | 0.054 | 0.157 | 1.94 | 5.2 | 0.054 | 0.157 | 1.95 | 2.6 | 0.054 | 0.157 | 1.95 | 3.9 | |

114.6 | 0.073 | 0.197 | 1.86 | 7.0 | 0.072 | 0.198 | 1.91 | 3.5 | 0.072 | 0.199 | 1.90 | 2.6 | |

155.4 | 0.090 | 0.242 | 1.84 | 23.2 | 0.090 | 0.242 | 1.84 | 4.5 | 0.090 | 0.241 | 1.83 | 4.5 | |

0.33 | 53.8 | 0.042 | 0.127 | 2.02 | 3.7 | 0.041 | 0.129 | 2.07 | 3.7 | 0.041 | 0.129 | 2.08 | 3.7 |

77.0 | 0.054 | 0.159 | 1.99 | 6.5 | 0.054 | 0.158 | 1.97 | 2.6 | 0.053 | 0.160 | 2.00 | 3.9 | |

114.6 | 0.073 | 0.199 | 1.87 | 7.0 | 0.072 | 0.201 | 1.90 | 4.4 | 0.071 | 0.203 | 1.92 | 2.6 | |

155.4 | 0.088 | 0.248 | 1.91 | 25.1 | 0.089 | 0.244 | 1.86 | 5.1 | 0.091 | 0.241 | 1.82 | 5.1 |

tanθ (-) | q_{1} (L/s/m) | Rack A (m = 0.16) | Rack B (m = 0.22) | Rack C (m = 0.28) |
---|---|---|---|---|

h/h_{c} (x = −0.50 m) | ||||

0 | 53.8 | 1.091 | 1.169 | 1.121 |

77.0 | 1.095 | 1.134 | 1.093 | |

114.6 | 1.072 | 1.106 | 1.087 | |

155.4 | 1.065 | 1.065 | 1.062 | |

0.10 | 53.8 | 1.130 | 1.142 | 1.122 |

77.0 | 1.099 | 1.105 | 1.098 | |

114.6 | 1.076 | 1.089 | 1.080 | |

155.4 | 1.041 | 1.041 | 1.044 | |

0.20 | 53.8 | 1.100 | 1.119 | 1.082 |

77.0 | 1.087 | 1.081 | 1.088 | |

114.6 | 1.072 | 1.048 | 1.059 | |

155.4 | 1.024 | 1.015 | 1.031 | |

0.30 | 53.8 | 1.100 | 1.119 | 1.082 |

77.0 | 1.087 | 1.081 | 1.088 | |

114.6 | 1.072 | 1.048 | 1.059 | |

155.4 | 1.024 | 1.015 | 1.031 | |

0.33 | 53.8 | 1.119 | 1.103 | 1.112 |

77.0 | 1.087 | 1.076 | 1.081 | |

114.6 | 1.062 | 1.056 | 1.049 | |

155.4 | 1.015 | 1.002 | 1.035 |

© 2017 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Castillo, L.G.; García, J.T.; Carrillo, J.M. Influence of Rack Slope and Approaching Conditions in Bottom Intake Systems. *Water* **2017**, *9*, 65.
https://doi.org/10.3390/w9010065

**AMA Style**

Castillo LG, García JT, Carrillo JM. Influence of Rack Slope and Approaching Conditions in Bottom Intake Systems. *Water*. 2017; 9(1):65.
https://doi.org/10.3390/w9010065

**Chicago/Turabian Style**

Castillo, Luis G., Juan T. García, and José M. Carrillo. 2017. "Influence of Rack Slope and Approaching Conditions in Bottom Intake Systems" *Water* 9, no. 1: 65.
https://doi.org/10.3390/w9010065