Ryy.py

import pandas as pd
import matplotlib.pyplot as plt
import scipy
import numpy as np
from scipy import integrate
from .uniqueFinder import uniqueFinder

def Ryy(data):

    data = data.copy()
    data = data[data['DisplacementLDA [V]'] != 0.00]
    data.reset_index(drop=True, inplace=True)

    data = data.sort_values('DisplacementLDA [V]').reset_index(drop=True)
    data = uniqueFinder(data)
    data['depth[cm]'] = data['uniqueDisplacement'].groupby(data['uniqueDisplacement']).transform(lambda x:np.round(-2.4953*x+25.753,2))

    ## Velocity components calcuation
    data['U'] = data['Vel1 [V]'].groupby(data['depth[cm]']).transform(lambda x: 0.096*(data['Vel2 [V]']-x))
    data['V'] = data['Vel1 [V]'].groupby(data['depth[cm]']).transform(lambda x: 0.096*(x+data['Vel2 [V]']))

    ## Velocity fluctuation calcuation
    data['uprime'] = data['U'].groupby(data['depth[cm]']).transform(lambda x: x - x.mean())
    data['vprime'] = data['V'].groupby(data['depth[cm]']).transform(lambda x: x - x.mean())

    data['vv_prime'] = data['vprime']*data['vprime']  ## Stress calculation

    #waterDepth = data['depth[cm]'].groupby(data['depth[cm]']).mean().iloc[-1] ## water depth

    '''
        To calculate the average velocity
    '''
    totalDepth = data['depth[cm]'].groupby(data['depth[cm]']).mean().iloc[-1] - data['depth[cm]'].groupby(data['depth[cm]']).mean().iloc[0]
    u_avg = scipy.integrate.simps(np.abs(data['U'].groupby(data['depth[cm]']).mean()), data['depth[cm]'].groupby(data['depth[cm]']).mean()) / totalDepth

    '''
        To calculate friction velocity
    '''
    upstreamWL = np.mean(38.01-3.76*data['WaterLevel1 [v]'])
    #print('upStreamWL', upstreamWL)
    downstreamWL = np.mean(36.42-3.8*data['WaterLevel3 [V]'])
    #print('downStreamWL', downstreamWL)
    diffWL = np.abs(upstreamWL - downstreamWL)
    waterDepth = (upstreamWL + downstreamWL)/2
    dx = 6  # horizontal length between two water levels
    dHdx = (diffWL/100)/dx # energy slope : water level is in centimeter, therefore need to change in meter
    #print('energy gradient', dHdx)
    R = (waterDepth/100 * 0.4)/(2*waterDepth/100 + 0.04) # hydraulic radius R = Area/Perimeter
    Ustar = np.sqrt(9.81*(waterDepth/100)*dHdx)

    return data['vv_prime'].groupby(data['depth[cm]']).mean(), waterDepth, u_avg