Arithmetic exception from relax()

[HANGPENG JIANG]

Hi Basilisk users,

I am currently simulation a droplet evaporation/combustion which has a super high density ratio( 2000 to 0.4).

The simulation went safely at the beginning, but always ended up somewhere saying:

Program terminated with signal SIGFPE, Arithmetic exception.

#0  0x0000000000418a02 in relax (al=<optimized out>, bl=<optimized out>, l=10, data=<optimized out>) at /home/hjiang/edoSandbox/basilisk/src/poisson.h:315

315       n += alpha.x[1]*a[1] + alpha.x[]*a[-1];

more details are like:

#0  0x0000000000418a02 in relax (al=<optimized out>, bl=<optimized out>, l=10, data=<optimized out>) at /home/hjiang/basilisk/src/poisson.h:315

#1  0x0000000000455bb5 in mg_cycle (a=a@entry=0x7ffddb9f33a0, res=res@entry=0x1d34890, da=da@entry=0x1d2c930, relax=relax@entry=0x418280 <relax>, 

    data=data@entry=0x7ffddb9f33f0, nrelax=nrelax@entry=24, minlevel=1, maxlevel=10) at /home/hjiang/basilisk/src/poisson.h:79

#2  0x0000000000456369 in mg_solve (a=a@entry=0x7ffddb9f33a0, b=b@entry=0x7ffddb9f33a8, residual=residual@entry=0x439010 <residual>, 

    relax=relax@entry=0x418280 <relax>, data=data@entry=0x7ffddb9f33f0, nrelax=<optimized out>, res=0x1d34890, minlevel=1, tolerance=1e-08)

    at /home/hjiang/basilisk/src/poisson.h:182

#3  0x00000000004566d3 in poisson (a=a@entry=..., b=b@entry=..., alpha=..., alpha@entry=..., lambda=..., tolerance=tolerance@entry=0, nrelax=nrelax@entry=4, 

    minlevel=0, res=0x0, flux=0x0) at /home/hjiang/basilisk/src/poisson.h:451

The tolerance I am using for diffusion() is 1e-8.

I have no idea why this relax() causes arithmetic exception, does it relevant to the super high density ratio?

Could anyone please help me with this issue?

Best,

Hangpeng