Prandtl Number

WHAT IS PRANDTL NUMBER???

The Prandtl number Pr is a dimensionless number; the ratio of momentum diffusivity (kinematic viscosity) to thermal diffusivity. It is named after the German physicist Ludwig Prandtl.

It is defined as:

\mathrm{Pr} = \frac{\nu}{\alpha} = \frac{\mbox{viscous diffusion rate}}{\mbox{thermal diffusion rate}} = \frac{c_p \mu}{k}

where:

ν : kinematic viscosity, ν = μ / ρ, (SI units : m2/s)
α : thermal diffusivity, α = k / (ρcp), (SI units : m2/s)
μ : dynamic viscosity, (SI units : Pa s = (N s)/m2)
k: thermal conductivity, (SI units : W/(m K) )
cp : specific heat, (SI units : J/(kg K) )
ρ : density, (SI units : kg/m3 ).

Note that whereas the Reynolds number and Grashof number are subscripted with a length scale variable, Prandtl number contains no such length scale in its definition and is dependent only on the fluid and the fluid state. As such, Prandtl number is often found in property tables alongside other properties such as viscosity and thermal conductivity.

 

Matrix in Dev Cpp

#include<stdio.h>
#include<conio.h>

int main()
{
    int i,j;

  int x[2][2];
  int y[2][2];  
  int z[2][2]={z[0][0],z[0][1],z[1][0],z[1][1]};
  printf("Enter 4 elemrnts of X[2][2]\n");
  scanf("%d%d%d%d",&x[0][0],&x[0][1],&x[1][0],&x[1][1]);
   printf("Enter 4 elemrnts of Y[2][2]\n");
  scanf("%d%d%d%d",&y[0][0],&y[0][1],&y[1][0],&y[1][1]);
  z[0][0]=x[0][0]+y[0][0];
  z[0][1]=x[0][1]+y[0][1];
  z[1][0]=x[1][0]+y[1][0];
  z[1][1]=x[1][1]+y[1][1];

 
       
            printf("|%d %d | |%d %d | |%d %d  |",x[0][0],x[0][1],y[0][0],y[0][1],z[0][0],z[0][1]);
            printf("\n|    |+|    |=|     |");
            printf("\n|%d %d | |%d %d | |%d %d |",x[1][0],x[1][1],y[1][0],y[1][1],z[1][0],z[1][1]);
           
                 
            getch();
            return 0;
 
    }

Bubble sort in Dev Cpp

#include<stdio.h>
#include<conio.h>
num.length( );
{
      int i, j, flag = 1;    // set flag to 1 to start first pass
      int temp;             // holding variable
      int numLength = num.length( );
      for(i = 1; (i <= numLength) && flag; i++)
     {
          flag = 0;
          for (j=0; j < (numLength -1); j++)
         {
               if (num[j+1] > num[j])      // ascending order simply changes to <
              {
                    temp = num[j];             // swap elements
                    num[j] = num[j+1];
                    num[j+1] = temp;
                    flag = 1;               // indicates that a swap occurred.
               }
          }
     }
     getch ()
     return 0; //arrays are passed to functions by address; nothing is returned
}

Multiple Array in Dev Cpp

#include<stdio.h>
#include<conio.h>
int main()
{
 
    int a[2][2]={{1,2},{3,4}};
   int b[2][2]={{4,5},{6,7}};
    int c[2][2]={{0},{0}};
    int i=0,j=0;
   
   
    for (i=0;i<2;i++)
    {
           for (j=0;j<2;j++)
            printf("%d\t",a[i][j]);
            printf("\n");
            }      
       
        printf("\n");  
           
    for (i=0;i<2;i++)
    {
           for (j=0;j<2;j++)
            printf("%d\t",b[i][j]);
            printf("\n");
            }            
            printf("\nthe sum of 2 matrices is\n ");

    for (i=0;i<2;i++)
    {
           for (j=0;j<2;j++)
           {
            c[i][j]=a[i][j]+b[i][j];
            printf("%d\t",c[i][j]);
            }
            printf("\n");
            }    
           
           
            getch();
            return 0;
            }

Dev CPP Programming languages

#include<stdlib.h>
#include<stdio.h>
#include<conio.h>
int main()
{
 char reg[20];
    char name[40];
    char subject[][4] = {"TP","PT","CPT","ICP","CS"};
    int marks[5];
    int total=0;
    float average=0.00;
    printf("\t\t\t\t\tMARKS SHEET");
    printf("\n\n\nEnter the name:");
    scanf("%s",name);
    printf("\n\nenter the registration no:");
    scanf("%s",reg);
   
    printf("Enter five marks\n");
   
   
   
    for (int i=0;i<5;i++)
    {
       
        printf("\nEnter Marks of %s:\n",subject[i]);
        scanf("%d",&marks[i]);
        total=total+marks[i];
        }
        average=total/5;
    system ("cls");
    printf("\t\t\t\tMARKS SHEET");
    printf("\n\n\n name:%s",name);
    printf("\n\n reg no:%s",reg);
   

    printf("\n\n subjects \t\t\t  Marks");
    for (int i=0;i<5;i++)
   
    {
        printf("\n\n  %s \t\t\t             %d ",subject[i],marks[i]);
}
  printf("\n\n\t\t\t Total = %d",total);
  printf("\n\n\t\t\t Average= %.1f",average);
    getch();
    return 0;
}

Invention of Cell

BACKGROUND OF INVENTION OF CELL

The conventional construction of a flashlight-type cell involves a zinc anode can with a depolarizer mix filling most of the can and having a carbon rod in the center as a current collector for the depolarizer mix. The cell is sealed by a soft asphaltic pitch and a metal cap which fits over the carbon rod and serves as the positive terminal. An airspace is provided above the depolarizer mix and below the pitch to permit the collection of gases and cell exudate. The gases are formed during discharge of the cell and means have to be provided for venting the gases before too large a pressure develops within the cell. If the cell is rechargeable, more gases may be evolved during charging and it becomes more important that the gases be vented properly.

There are disadvantages in the conventional cell construction. In particular, several assembly stations are required for placing a seal washer down into the cell, pouring the asphaltic pitch onto the seal washer, placing a vent washer on top of the pitch and finally placing the terminal cap on top of the cell and locking it in place. The vent washer on top of the pitch is used to prevent the cap from becoming embedded in the pitch to form a gastight seal which could prevent venting.

The use of the asphaltic pitch makes the sealing operation dirty and somewhat expensive due to the several steps required in the operation. In addition, the soft pitch does at times squeeze up around the top washer and cause a gastight seal around the terminal cap edge. Another disadvantage is that high temperatures may soften the pitch and cause it to leak from the cell container.

Dry Cell

Dry cell batteries A dry cell is the most common type of battery used today, according to Robert Asato, Ph.D., of Leeward Community College, in Pearl City, Hawaii. Dry cell batteries power small portable electronic devices, such as flashlights, audio players, watches, cameras and TV remotes. Disposable or rechargeable, dry cells range from pencil tip-sized batteries used in medical applications to enormous batteries designed to provide backup for cities in case of power outages.

    History According to Energizer, archaeological digs suggest batteries were invented in some form at least 2,000 years ago, but the forerunners of batteries we know today began in 1798 with Count Alessandro Volta's "voltaic pile," a crude battery made with copper and a salt or acid solution. French chemist Georges Leclanche's 1868 design of the "wet" cell battery was the forerunner of the first "dry" cell, invented in 1888 by German scientist Carl Gassner, which was similar to modern carbon-zinc batteries.

Types Asato points to the carbon-zinc battery, with ammonium chloride providing the dry "paste" for the chemical reaction, as common type of dry cell. Alkaline batteries last longer, however, because the electrolyte sodium hydroxide or potassium hydroxide used is less corrosive of the zinc. Other types include silver batteries, mercury cell batteries often used for calculators, and nickel-cadmium and nickel metal hydride batteries, which can be recharged.

       FUNCTION A standard dry cell battery works by providing an electrochemical reaction when inserted into a device and completing a circuit between the cathode (often carbon), and anode (often zinc), separated by an electrolyte, which generates an electric current collected elsewhere in the cell that can then conduct the electricity to the exterior circuit.

Disposable or Rechargeable    Commonly, low voltage and rarely used devices such as flashlights use disposable carbon-zinc dry cell batteries as well as the longer-lasting alkaline dry cell batteries. The Green Living Tips website states that nickel cadmium (Nicads) or nickel metal hydride (NiMH) batteries are the most frequently purchased rechargeables, sold in most if not all the same sizes as disposables. Rechargeable batteries generally save you money, if the device being powered is used so often that fresh batteries are constantly required.

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