how to get current web in clientcontex managed csom in sharepoint2013

hi,

i have one site collection which is having multiple webs .

like http://servername:port/Depart

when i doing crud operation at one sub site .modifications are taking plaace to root level web but not in current web site where i am doing, how to get the current web.

here is sample code which i have eimplemented in business layer

using (ClientContext clientContext = new ClientContext(sharepointSiteUrl))
                {
                    ValidateAuthentication(authenticationDetails, clientContext);                      
                    List list = clientContext.Web.Lists.GetByTitle(listName);              

    }

Srinivas