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+\chapter{Installing and Running Gmsh}
+\thispagestyle{empty}
+\label{sec:chap4}
+\newcommand{\LocCHfourfig}{\Origin/CHAPTERS/chap4/figures}
+
+Gmsh is a Free and Open Source three dimensional finite element grid generator with a build-in CAD engine and post-
+processor. There are four modules available in Gmsh such as Geometry, Meshing, Solver and Post-Processiing. Using
+Gmsh we can mesh the geometry and import it in OpenFOAM using the mesh conversion utilities (see chapter 17 for more info).
+In this chapter we will cover how to install Gmsh and create a simple geometry.It is expected that the user should have knowledge 
+about Meshing.
+
+\section{Installing Gmsh}
+
+Gmsh can be installed using Synaptic Package Manager. Open Gmsh in your system by typing your system passowrd.
+In the search box type Gmsh and install it, Fig \ref{synaptic-gmsh}. This might take some time depending on your internet speed.
+
+\begin{figure}[ht]  
+\begin{center}  
+\includegraphics[scale=0.32]{\LocCHfourfig/synaptic-gmsh.png}
+\caption{Install Gmsh}
+\label{synaptic-gmsh}
+\end{center}  
+\end{figure}
+
+
+\flushleft Alternately we can also install Gmsh from the gmsh website given below,
+
+\center {\textbf{http://geuz.org/gmsh/}} \newline
+
+\flushleft Open this website in your browser and scroll down to download. Now Download Gmsh according to the given current stable release 
+Fig \ref{download-gmsh} according to your Operating System (OS).
+
+\begin{figure}[ht]  
+\begin{center}  
+\includegraphics[scale=0.352]{\LocCHfourfig/download-gmsh.png}
+\caption{Download stable release}
+\label{download-gmsh}
+\end{center}  
+\end{figure}
+
+\begin{figure}[ht]  
+\begin{center}  
+\includegraphics[scale=0.26]{\LocCHfourfig/gmsh-icon.png}
+\caption{gmsh-icon}
+\label{gmsh-icon}
+\end{center}  
+\end{figure}
+
+
+\flushleft In the Download folder extract the downloaded gmsh tar file. After you open the folder you will see folder named bin, click on it. 
+Inide the bin folder you will see the Gmsh icon, Fig \ref{gmsh-icon}. Double click on it to launch the Gmsh Start screen, Fig \ref{gmsh-start} \newline
+
+As a pracice to learn Gmsh we will create a cube of sides 1 unit as seen in the Fig, \ref{geometry1}. On the left hand side in the Gmsh window you can 
+see three modules namely,
+
+\begin{itemize}
+\item Geometry
+\item Mesh
+\item Solver
+\end{itemize}
+
+Click on the Geometry module, then go to Elementary Entities, inside elementary entities go to add and then click on points. This will open up a
+window where you can enter the X, Y and Z co-ordinates starting with 0 inside each box and press Enter, Fig \ref{point}. Now
+enter points for all the remaining 7 vertices to complete the cube, Fig \ref{geometry1}. In the Gmsh screen we can see the eight points, you can move those points
+using the left mouse click. To join these points click on Straight-line option under Elementary Entities. Now select any two points to create a straight line, click 
+on the start point and then the second point to create a line. Similarly join all the other points to create a cube as shown in the Fig, \ref{line} below.
+As you can see on the Gmsh screen you can press e to end selection and q to abort.
+
+\begin{figure}[t]  
+\begin{center}  
+\includegraphics[scale=0.28]{\LocCHfourfig/gmsh-start.png}
+\caption{gmsh-icon}
+\label{gmsh-start}
+\end{center}  
+\end{figure}
+
+\begin{figure}[t]  
+\begin{center}  
+\includegraphics[scale=0.28]{\LocCHfourfig/geometry1.png}
+\caption{Cube of unit dimension}
+\label{geometry1}
+\end{center}  
+\end{figure}
+
+\begin{figure}[t]  
+\begin{center}  
+\includegraphics[scale=0.28]{\LocCHfourfig/point-gmsh.png}
+\caption{Points window}
+\label{point}
+\end{center}  
+\end{figure}
+
+\begin{figure}[t]  
+\begin{center}  
+\includegraphics[scale=0.28]{\LocCHfourfig/cube-gmsh.png}
+\caption{Join the points using line}
+\label{line}
+\end{center}  
+\end{figure}
+
+\subsection{Create Faces}
+
+To create faces for the cube click on plane-surface unde elementery enetities. After this select the outer booundaries of the face of a rectangle.
+Select the edges of the bottom face first.Once you select the edges they will turn red in color, Fig \ref{face}. Check in case if there is any hole in the 
+face, if none then press e to end selection. You will notice that a face will appear with dasshed center lines, Fig \ref{cl}. Repeat this procedure for 
+remaining faces, Fig \ref{face-all} and finally press q to abort.
+
+\begin{figure}[t]  
+\begin{center}  
+\includegraphics[scale=0.28]{\LocCHfourfig/face-red.png}
+\caption{Selct edges}
+\label{face}
+\end{center}  
+\end{figure}
+
+
+\begin{figure}[t]  
+\begin{center}  
+\includegraphics[scale=0.28]{\LocCHfourfig/face-cl.png}
+\caption{Bottom Face}
+\label{cl}
+\end{center}  
+\end{figure}
+
+\begin{figure}[t]  
+\begin{center}  
+\includegraphics[scale=0.28]{\LocCHfourfig/face-all.png}
+\caption{Create faces for all surfaces}
+\label{face-all}
+\end{center}  
+\end{figure}
+
+\subsection{Creating Volume}
+
+We now need to create volume boundary. We need to select the Volume boundary similar to selecting boundary for faces. 
+Click on the Volume boundary under elementery entities and click on boundary surface of the cube and press e to end selection. A yellow dot will
+appear at the center of the cube which represents volume in Gmsh. Press q to abort the selction.
+
+\begin{figure}[t]  
+\begin{center}  
+\includegraphics[scale=0.28]{\LocCHfourfig/vol-gmsh.png}
+\caption{Volume}
+\label{vol}
+\end{center}  
+\end{figure}
+
+\subsection{Physical Groups}
+
+In Gmsh we need to create physical groups which will be useful for exporting the Mesh file to OpenFOAM. To do so click on Physical Group under Geometry Module.
+Click on Add and then Surface. Upon selection of any face it will turn red. Now press e to end selection. Do this procedure for all the remaining faces
+and press q to abort. Also we need to select the Physical Volume. Click on Volume under Physical Groups and select the yellow dot at the center of the cube.
+The yellow dot will turn red in colora dn press e to end selection and q to abort.
+
+To save the geometry under the file menu click on Save as and save the geometry by the name cube.geo. Here "geo" stands for geometry. Click OK twice
+to save the geometry. 
+
+