eki 0.2.0

Eki is a solver for steady and transient flow in fluid networks.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158

use std::f64::consts::PI;
use crate::node::Node;
use crate::fluid::Fluid;

#[derive(Clone, PartialEq, Debug, Default, serde::Serialize, serde::Deserialize)]
#[cfg_attr(feature = "persistence", serde(default))]
pub struct Pump {
    pub from: Node,
    pub to: Node,
    pub mass_flow: Vec<f64>,
    pub head_data: Vec<(f64, f64)>, // (Q, dH)
    //pub a: Vec<f64>,            // Vector of coefficients
    pub diameter: f64,          // TODO ??? inlet/outlet diameter ???
    pub thickness: f64,         // TODO ???
    pub youngs_modulus: f64,    // TODO ???
}

impl Pump {
    pub fn new( from: Node, to: Node ) -> Self {
        Pump {
            from,
            to,
            mass_flow: vec![ 0.0 ],
            head_data: vec![ 
                (0.000, 1.0e16),
                (0.111, 700.),
                (0.222, 160.),
                (0.333, 60.),
                (0.444, 23.),
                (0.556, 7.9),
                (0.667, 3.),
                (0.778, 1.4),
                (0.889, 0.5),
                (1.000, 0.25),
            ],
            //a: vec![ 1.0, 0.0, -1.0 ],
            diameter: 1.0,                  // TODO ??? 
            thickness: 1.0,                 // TODO ???
            youngs_modulus: 1.0,            // TODO ???

        }
    }

    pub fn new_data( from: Node, to: Node, head_data: Vec<(f64, f64)> ) -> Self {
        Pump {
            from,
            to,
            mass_flow: vec![ 0.0 ],
            head_data,
            diameter: 1.0,                  // TODO ??? 
            thickness: 1.0,                 // TODO ???
            youngs_modulus: 1.0,            // TODO ???

        }
    }

    pub fn resistance(&self, flow_rate: f64, _nu: f64, _g: f64 ) -> f64 {
        //self.a[0] + self.a[1] * flow_rate + self.a[2] * flow_rate * flow_rate.abs()
        //println!( "flow_rate = {}", flow_rate );
        //let r = self.interpolate_data( flow_rate );
        //println!("r = {}", r );
        //r
        
        self.interpolate_data( flow_rate )
    }

    //TODO interpolation utility function
    //TODO what about negative values and out of range values
    pub fn interpolate_data(&self, flow_rate: f64 ) -> f64 {
        let mut xlower = self.head_data[0].0;
        let mut xupper = self.head_data[1].0;

        let mut ylower = self.head_data[0].1;
        let mut yupper = self.head_data[1].1;
        
        for (index, k_value) in self.head_data.iter().enumerate() {
            if k_value.0 < flow_rate {
                xlower = self.head_data[index].0;
                ylower = self.head_data[index].1;
            } else {
                xupper = self.head_data[index].0;
                yupper = self.head_data[index].1;
                break;
            }
        }

        if xlower == xupper {
            ylower
        } else {
            let dy = ylower - yupper;
            let dx = xlower - xupper;
            let m = dy / dx;
            let y = yupper + m * (flow_rate - xupper);
            y
        }
    }

    pub fn area(&self) -> f64 {
        PI * self.diameter * self.diameter / 4.0
    }

    pub fn wave_speed(&self, fluid: &Fluid ) -> f64 {
        let k_over_rho: f64 =  fluid.bulk_modulus() / fluid.density();
        let dk: f64 = self.diameter * fluid.bulk_modulus();
        let te: f64 = self.thickness * self.youngs_modulus;
        let a = k_over_rho / ( 1.0 + ( dk / te ) );
        a.sqrt()
    }

    //TODO ???
    pub fn k_laminar(&self, nu: f64 ) -> f64 {
        PI * 9.806 * self.diameter.powi( 4 ) / ( 128.0 * 1.0 * nu )
        /*let design_flow = 50. / ( 60. * 60. );
        let design_head = 50.;
        - design_flow / design_head*/
        //2.14e-4
    }

    //TODO ???
    pub fn darcy_approx(&self, head_loss: f64, _g: f64 ) -> f64 {
        /*let f = 0.1;        // assumed friction factor for initial guess
        let a = self.area();
        let result = 2.0 * g * self.diameter * a * a / ( f * 1.0 * head_loss.abs() );
        result.sqrt()*/
        //println!( "head_loss = {}", head_loss );
        - self.interpolate_head( head_loss.abs() )
    }

    pub fn interpolate_head(&self, head_loss: f64 ) -> f64 {
        let mut xlower = self.head_data[0].1;
        let mut xupper = self.head_data[1].1;

        let mut ylower = self.head_data[0].0;
        let mut yupper = self.head_data[1].0;
        
        for (index, k_value) in self.head_data.iter().enumerate() {
            if k_value.0 < head_loss {
                xlower = self.head_data[index].1;
                ylower = self.head_data[index].0;
            } else {
                xupper = self.head_data[index].1;
                yupper = self.head_data[index].0;
                break;
            }
        }

        if xlower == xupper {
            ylower
        } else {
            let dy = ylower - yupper;
            let dx = xlower - xupper;
            let m = dy / dx;
            let y = yupper + m * (head_loss - xupper);
            y
        }
    }

}