Question on the background of CohFrictMat contact model

Hi,
Most of the constitutive relations are described in Bourrier2013 [1].
The law is more general than what you'll find in the paper but you will
have a big part of it.
Don't hesitate to ask more details if this paper is not enough.
Bruno

[1] http://dx.doi.org/10.1016/j.ecoleng.2013.05.002

    Many thanks to Dr. Bruno.
    I have read some references on the contact model of the cohesive material in DEM, for example the algorithm in PFC and other DEM code. And I have found that there are some different on the calculation of the normal and shear adhesion forces:
    In PFC the normal and shear adhesion fores are calculated according to the "area" of the contact ( which is understanded easily):
       normalAdhesion =min(normalCohesion_A,normalCohesion_B)*Pi*pow(min(D_B, D_A),2);
      shearAdhesion =min(shearCohesion_A,shearCohesion_B)*Pi*pow(min(D_B, D_A),2);
   However in YADE the adhension forces are calculated according the "square" of the contact diameter[1]:

      contactPhysics->normalAdhesion = std::min(sdec1->normalCohesion,sdec2->normalCohesion)*pow(std::min(Db, Da),2);
      contactPhysics->shearAdhesion = std::min(sdec1->shearCohesion,sdec2->shearCohesion)*pow(std::min(Db, Da),2);

    Is there any introductions on the reasons of this different?

Thanks a lot!

Henry

[1] http://bazaar.launchpad.net/~yade-pkg/yade/git-trunk/view/head:/pkg/dem/CohesiveFrictionalContactLaw.cpp

What is the difference? A multiplication by pi?!
There is no rational behind assuming a circular, rectangular, or elipsoidal cross section.
The two things scale exactly the same, that is what matters.

Many thanks for the help from Bruno.
Best Regard,
Henry