#!/usr/bin/env python
# coding: utf-8

# 
# # Assignment 1(b): Wave added mass and damping
# 
# You will use the functions from the Wave Greens Function notebook to check the data from the roll damping lab and predict the damping characteristics of a 2D ship section across a range of parameters.
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# 1. **To be completed per 7 or 8-person lab session:** Determine the natural frequency $\omega_n$ of the model and damping ratio $\zeta$ at this frequency using both the free-decay and forced oscillation roll data. Approximate the model midship geometry, and predict the added-inertia and damping coefficients $A_{44},B_{44}$ at the observed natural frequency. Use the model's bouyant stiffness $mgl_{GM}$ and moment of inertia $I$ to compare the _calculated_ and _measured_ natural frequency $\omega_n^2=\frac{mgl_{GM}}{I+A_{44}}$ and damping ratio $\zeta=\frac 1{2\omega_n} \frac{B_{44}}{I+A_{44}}$. Discuss the potential sources of error in this approach.
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# 1. **To be completed per 2 or 3-person group:** Create a "maritime section" of your choice and demonstrate how the geometry changes over a dimensionless geometric parameter. An example is the aspect ratio of an semi-submerged ellipse, *although you may not use this shape as your geometry*. Determine the surge, sway, and/or roll added mass and damping coefficients as a function of the nondimensional frequency and the geometric parameter. Discuss any important changes in the coefficients and their physical cause. Identify a worst-case excitation for your geometry and a potential mitigation.
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# ## Due 23:59, 17 Mar 2022
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# * Submit separate write-up files for Q1 and Q2.
# * You can use a whatever method you want to identify the amplitudes and frequencies from the roll data, but you need to explain your approach and submit a file with the final tabulated data which appears in your Q1 plots. 
# * Submit any code needed to replicate your section geometries, added mass and damping results, and plots.

# In[ ]:


# Import functions
import requests
url = 'https://raw.githubusercontent.com/weymouth/MarineHydro/master/src/WaveMethod.py'
exec(requests.get(url).content)