# Assemble_LHS

| main | Tutorials | Functions | website |

Assembles the conductance matrix

Version : 1.0

Author : George Kourakos

email: giorgk@gmail.com

web : http://groundwater.ucdavis.edu/msim

Date 18-Mar-2014

Department of Land Air and Water

University of California Davis

## Contents

## Usage

[Kglo H]= Assemble_LHS(p, MSH, K, CH, GHB, opt)

## Input

* p*: [Np x 3] Coodrinates of nodes [x1 y1 z1; x2 y2 z2;...xn yn zn], where Np is the number of nodes

* MSH*: [Nel x Np_el] id of elements. Each row correspond to an element. Nel is the number of elements and Np_el is the number of dofs per element

* K* : Hydraulic Conductivity defined on nodes or elements, If size(

*,1)==Np then K is defined on nodes. If size(*

**K***,1)=Nel then K is defined on elements. If size(*

**K***,2)==1 then aquifer is isotropic Kx=Ky=Kz. If size(*

**K***,2)==2 then aquifer is anisotropic Kx=Ky~=Kz. If size(*

**K***,2)==3 then aquifer is anisotropic Kx~=Ky~=Kz.*

**K*** CH*: [nx2] the first column contains the id of the nodes with constant head boundary conditions. The second contains the values

* GHB*: [nx3] : id of node connected with a GHB, head, conductance

* opt* : Simulation options with the following fields:

*dim*: Dimension of the problem : 1, 2 or 3.

*el_type*: type of element e.g. triangle, prism etc...

*el_order*: order of the element: linear or quadratic

*assemblemode*: 'vect', 'nested','serial'(Use always vect)

## Output

* Kglo*: Global conductance matrix (sparse)

*: vector with nan values for the unknowns and scalar for the dirichlet nodes*

**H**