Fluids on the sphere

My primary research line is related to numerical global atmospheric modelling, mainly using unstructured polygonal spherical grids (such as the one shown below) to solve the differential equations.

 

icos
Icosahedral grid (spherical Delaunay triangulation with Dual Voronoi Tesselation)

In real application, we could have locally refined grids, such as the one shown in the next figure.

icos_ref_scvt_h1_4
Spherical Centroidal Voronoi Tessellation with local refinement

I have been particularly interested in how certain grid structures interfere in the solution of the PDEs. The figures below shows the error of a usual finite volume discretization of the divergence operator for o solid body rotation flow. Note that there are well defined grid related structures, called grid imprinting.  See Peixoto and Barros (2013) for details here.

 

divrothx
Divergence error for rotation in icosahedral grid
vrecon_perhxlintrv_b_f8_HC_nwerror_icos_ref_scvt_h1_8
Divergence grid imprinting in SCVT grid

 

 

 

 

 

 

 

 

 

I have also worked with a semi-Lagrangian transport model in this kind of grid. The figure below shows a results of a deformational test case example. See Peixoto and Barros (2014) for details here.

trans_v4_in2_tj1_nt512_hermtrv_mt0_perhxlsqhxelintrv_mfx0_phi_t256_icos_pol_nopt_7
Deformational transport test case

 

More recently, I have been working with a modification of mimetic finite volume schemes for the shallow water equations, to allow better accuracy (see Peixoto (2016) for details here). Below are results for the barotropically unstable jet test case.

swm_tc21_dt100_HC_vrecperhx_crecpered_sintbary_grdtrsk_pv_ed_t518400_HR95JT_007
Potential Vorticity for barotropically unstable jet

 

Please see more details of the things I have been investigating in my papers with collaborators. Do not hesitate to contact me if you wish to discuss anything related to this research topic.

You can find the software I developed to work on these grids and all the experiments up until the shallow water model here.