# To Do¶

(this list is automatically coollected from the documentation)

Todo

For completeness mention JKR model; mention Maugis model as the one which accounts for the transition between both, COS introducing the $$\alpha$$ parameter, Schwarz (below) giving analytical solution.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/theory/contact/adhesive.rst, line 41.)

Todo

Such tension/compression test can be found in the ysrc{examples/concrete/uniax.py} script.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/theory/contact/concrete.rst, line 591.)

Todo

The code has a different formulation: one contribution of $$\frac{1}{2}\frac{f_t-f_y}{k_t}(f_t-f_y)$$ and another of $$f_y\frac{f_t-f_y}{k_t}$$, giving together

$\Delta E_{pt}=\left(\frac{f_t-f_y}{2}+f_y\right)\frac{f_t-f_y}{k_t}.$

The difference of elastic potentials leads to yet another formulation:

$\Delta E_{pt}=\frac{1}{2}\frac{f_t^2}{k_t}-\frac{1}{2}\frac{f_y^2}{k_t}=\frac{f_t^2-f_y^2}{2k_t}.$

Decide analytically on which of those is the best approximation and use it both in the code and in the docs.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/theory/contact/linear.rst, line 193.)

Todo

This computation can be (perhaps substantially) sped up by using other iterative methods, such as Newton-Raphson, finding root of $$S'(\lambda)$$, and re-using the value from the previous step as the initial guess. There are also papers suggesting better algorithms such as [ZIPM09].

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/theory/geom/ellipsoid.rst, line 32.)

Todo

Write.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/theory/geom/ellipsoid.rst, line 75.)

Todo

Is it ok that relative velocities are initially zero, and not updated until in the next step? Those could be computed directly, although with less precision, when the contact is formed.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/theory/geom/l6geom.rst, line 46.)

Todo

Something along the following lines (note that htis semsntics – negative value of distFactor – is not yet implemented): Contact criterion for spheres: When there is not yet contact, it will be created if $$u_n=|\curr{\vec{x}}_2-\curr{\vec{x}}_1|-|f_d|(r_1+r2)<0$$, where $$f_d$$ is interaction radius (sometimes also called “interaction radius”). If $$f_d>0$$, then $$\vec{u}_{0x}$$ will be initalized to $$u_N$$, otherwise to 0. In another words, contact will be created if spheres enlarged by $$|f_d|$$ touch, and the “equilibrium distance” (where $$\vec{u}_x-\vec{u}_{0x}=0$$) will be set to the current distance if $$f_d>0$$ is positive, and to the geometrically-touching distance if $$f_d<0$$. Initial contact point is $$\vec{c}=\vec{x}_1+\left(r_1+\frac{\vec{u}_{0x}}{2}\right)\normalized{\vec{x}_2-\vec{x}_1}$$.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/theory/geom/sphere.rst, line 10.)

Todo

distFactor is not yet implemented as described above; some formulas mix values at different times, should be checked carefully.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/theory/geom/sphere.rst, line 12.)

Todo

To be completed or moved somewhere else.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/theory/granular/psd.rst, line 8.)

Todo

Mention how are forces from contacts summed up.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/theory/leapfrog.rst, line 14.)

Todo

Write about clump motion integration; write about woo.dem.ClumpSpherePack and how its properties are computed. Perhaps move clumps to a separate file.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/theory/leapfrog.rst, line 244.)

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/theory/leapfrog.rst, line 249.)

Todo

Mostly from [Fel99a], chapter 9.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/theory/tet4-element.rst, line 60.)

Todo

write about woo.dem.CircularOrbit and how to use it on meshes (like mixer blades), be those clumped or not.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/tutorial/impose.rst, line 85.)

Todo

Formulas for computing principal axes position & orientation.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/user/clump.rst, line 37.)

Todo

Describe the grid sampling algorithm.

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/user/clump.rst, line 43.)

(The original entry is located in /home/runner/work/woo/woo/doc/sphinx2/source/user/clump.rst, line 61.)

Todo

Nested (grouped) series are not read correctly from HDF5. Should be fixed either by flattening the hiearchy (like we do in dbToSpread and stuffing it into returned dict; or by reflecting the hierarchy in the dict returned.

(The original entry is located in /home/runner/.local/lib/python3.8/site-packages/woo/batch.py:docstring of woo.batch.dbReadResults, line 5.)

Todo

Handle rotation which is not detected by verlet distance!

(The original entry is located in docstring of woo.dem.Bo1_Ellipsoid_Aabb, line 3.)

Todo

with cumulative=False and when the PSD does not $$x$$-start at 0, the plot is not correct as the hump coming from the jump in the PSD (from 0 to non-zero at the left) is not taken in account.

(The original entry is located in docstring of woo.dem.PyCapsule.inputPsd, line 3.)

Tip

Report issues or inclarities to github.