[CIG-SHORT] Rate and state friction friction.linear_slip_rate nondimentional?

[Ekaterina Bolotskaya]

Dear Brad,

Thanks a lot!

My simulation is elastic.
I there any physical meaning of relaxation_time (I'm currently just setting it for nondimentional slip rates to make sense with regard to each other)?

Thanks.

Best regards,
Ekaterina Bolotskaya

PhD student in Geophysics,
Earth, Atmospheric and Planetary Science Department,
Massachusetts Institute of Technology
E-mail. bolee at mit.edu
Mob. +1 (857) 284-2805
         +7 (963) 995-36-33

________________________________________
From: CIG-SHORT [cig-short-bounces at geodynamics.org] on behalf of Brad Aagaard [baagaard at usgs.gov]
Sent: Wednesday, February 28, 2018 19:04
To: cig-short at geodynamics.org
Subject: Re: [CIG-SHORT] Rate and state friction friction.linear_slip_rate nondimentional?

Ekaterina,

The linear_slip_rate value is used to regularize the log term as slip
rates approaches zero. It is most closely related to the solver
tolerances (which are nondimensional), which is why I chose to use a
nondimensional value. I would try using a value for the linear slip rate
that is about one order of magnitude larger than your SNES absolute
tolerance. I would expect these values to be a few orders of magnitude
smaller than the nondimensionalized reference slip rate. Slip rate is
nondimensionalized by dividing the slip rate in m/s by the velocity
scale (length scale in meters divided by the time scale in seconds).

Regards,
Brad


On 02/28/2018 03:50 PM, Ekaterina Bolotskaya wrote:
> Dear Pylith developers,
>
> I'm using rate and state friction model in my simulations.
> I found in the manual that friction.linear_slip_rate is a nondimentional
> quantity that should be about one order of magnitude larger than
> absolute tolerance in solve.
>
> Could you tell me how Pylith uses this nondimentional value
> (*friction.linear_slip_rate*) with my dimentional*slip rate* and
> *reference slip rate*? Or how does it nondimentionalize dimentional
> rates? And what should the relation between the three approximately be?
> I just want to make sure the three of them are reasonable with regard to
> each other.
>
> Thanks!
>
>
> Best regards,
> Ekaterina Bolotskaya
>
> PhD student in Geophysics,
> Earth, Atmospheric and Planetary Science Department,
> Massachusetts Institute of Technology
> E-mail. bolee at mit.edu
> Mob. +1 (857) 284-2805 <tel:%2B1%20%28857%29%20284-2805>
> +7 (963) 995-36-33 <tel:%2B7%20%28963%29%20995-36-33>

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