求教一段和梯度相关的UDF代码的含义，先谢过了~

代码内容如下：

DEFINE_ADJUST(adjust_for_force, domain)

{

Thread **pt;

Thread *t;

cell_t c0;

Domain *pDomain = DOMAIN_SUB_DOMAIN(domain,1);

/*  if turbulence begin */

Alloc_Storage_Vars(pDomain,SV_VOF_RG,SV_VOF_G,SV_NULL);

Scalar_Reconstruction(pDomain, SV_VOF,-1,SV_VOF_RG,NULL);

Scalar_Derivatives(pDomain,SV_VOF,-1,SV_VOF_G,SV_VOF_RG,Vof_Deriv_Accumulate);

mp_thread_loop_c (t,domain,pt)

if (FLUID_THREAD_P(t))

{

Thread *tp = pt[1];

begin_c_loop (c0,t)

{

C_UDMI(c0,t,0) =

Ctd*C_R(c0,pt[0])*C_K(c0,t)*C_VOF_G(c0,tp)[0] ;

C_UDMI(c0,t,1) =

Ctd*C_R(c0,pt[0])*C_K(c0,t)*C_VOF_G(c0,tp)[1] ;

#if RP_3D

C_UDMI(c0,t,2) = Ctd*C_R(c0,pt[0])*C_K(c0,t)*C_VOF_G(c0,tp)[2] ;

#endif

}

end_c_loop (c0,t)

}

Free_Storage_Vars(pDomain,SV_VOF_RG,SV_VOF_G,SV_NULL);

}

代码的大致含义我明白了，但是

Alloc_Storage_Vars(pDomain,SV_VOF_RG,SV_VOF_G,SV_NULL);

Scalar_Reconstruction(pDomain, SV_VOF,-1,SV_VOF_RG,NULL);

Scalar_Derivatives(pDomain,SV_VOF,-1,SV_VOF_G,SV_VOF_RG,Vof_Deriv_Accumulate);

这一段代码，在UDF手册和网络上都没有找到相关的介绍，所以特地再次求教一下，还请各位赐教

@刘腾炼 @胡坤 @仿真小刘