# [Example 4] Flow in a real river（single cross section)¶

## Select Solver¶

In the [Select Solver] window, Figure 81 , select [Nays2d+] and click [OK].

## Importing River Survey Data¶

In the window, Figure 82, select [Import], [Geographic Data], [Elevation(m)] Figure 82 : Import river geographic data

Chose [single.riv] in the window, Figure 83 and open. The cross sectional survey data “single.riv” can be downloaded from， https://i-ric.org/yasu/fw/rivfiles/single.riv

A message window may appear telling “Problems Fund i Data” as Figure 84 ,but just click [OK]

Select [Middle point of left and right bank] in the [River Survey Data Import Setting] window as Figure 85 , and click [OK] Figure 85 : River Survay Data Import Setting

Figure 86 riv file import complete.

## Grid Generation Conditions¶

From the main menu, select [Grid] and [Select Algorithm to Create Grid] as, Figure 87 Figure 87 : Select Algorithm to Create Grid

Select [Create grid from river survey data] from the window, Figure 88 , and click [OK]. Figure 88 : Create grid from river survey data

As shown in Figure 133 , a channel with cross sections with both ends’ blue circles are displayed. Figure 89 : Setting Grid Create Condition Complete

## Grid Generation¶

Select any side of one of the cross section line, right click, and chose [Add Division Points].

Set [Division Number], set  in this example, and click [OK] (Figure 91 )

Select one of the opposite side of the cross sectional line we selected in Figure 90 , right click, and chose [Add Division Points] (Figure 92 )

Set [Division Number], set  as a same number we set in Figure 91 for the symmetry.

Along the channel direction, division points are set all at once. Select [Grid], [Add Division Points Regionally] from the menu bar. ( Figure 94 ) Figure 94 :Add Division Points Regionally(1)

Chose [Specify target distance division points]. set distance  in this example, and click [OK]．( Figure 95 ) Figure 95 :Add Division Points Regionally(2)

When the setup for division points are completed, a plane map with yellow circle points appears as Figure 96 Figure 96 :Set division points complete

Select [Grid], [Grid Create] from the menu bar.( Figure 97 )

Confirm the grid generation range painted with blue, and click [OK].

Answer [Yes] when you asked [Do you want to map?] as Figure 99

Completed grid is shown as Figure 100

Bed configuration and channel shape can be confirmed by putting checking marks at, [Grid], [Node attributes] and [Elevation (m)]. ( Figure 101 ) Figure 101 :Confirmation of the Mapping Result

## Computational Condition¶

Select [Calculation Condition] and [Setting] from the min menu as Figure 102 . Figure 102 :Setting Computational Condition

Set [Time unit of discharge] as [Hour] and click , ( Figure 103 )

Set discharge hydrography as Figure 104, constant for 3 hours with 2,000 qms, and click [OK].

Set [Time and bed erosion condition] as Figure 105 . Figure 105 :Time and bed erosion condition

Set “3D Velocity Profile” as shown in the figure Figure 106 , and click [Save and Close] to exit. Figure 106 :3D Velocity Profile Settings

## Launch Computation¶

From the menu bar, select [Simulation] and [Run].

Simulation starts. Figure 109

Click [OK] when the message [The solver finished calculation] as Figure 110

## Display Computational Results¶

After the companion finished, form the main menu, by selecting [Calculation Results] and [Open new 2D Post-Processing Window], a new Window appears as Figure 111 .

### Depth¶

n the object browser, put the check marks in “Scalar (node)” and “Depth[m]”, right-click and select “Properties”. The “Scalar Setting” window Figure 112 appears.

Set the values as shown in Figure 112, and click [OK], then Figure 113 appears.

### Display Background Image¶

Select from the main menu, [File]->[Property] ( Figure 114 )

From the “Project Property” window, click  at [Coordinate System] .. _04_haikei_02: Figure 115 :Edit Coordinate System Setting

Input “Japan” in the [Search] window, and chose the one with “XII” from the items with [EPSG:….] as Figure 116 . See more detail on coordinate system of Japan at http://www.gsi.go.jp/sokuchikijun/jpc.html

Click [Close] of [Project Property] window of Figure 117

Put a check mark in a box in front of [Background Images(Internet)] and one of the items listed below, e.g., [Google Map (Satellite Image)] as Figure 118 Figure 118 :Background Image Import Complete

### Velocity Vectors and Streamlines¶

Since the operation method is the same as the previous section, it will be omitted.

### Particle Animations¶

Put check mark at [Particles] and [Velocity] in the object browser, put time bar back to zero, and push black button, ( Figure 119 ). Particle following the depth averaged velocity starts as Figure 120 . Figure 120 :Particle movement by depth averaged velocity

Put check mark at [Particles] and [Surface Velocity] in the object browser. If you want to change color of particles, right click [Particle] and select [Property]. Set values as Figure 121 and click [OK]. Put the time bar back again to zero, and push black button. Particle following the surface velocity starts as Figure 122 . Figure 122 :Particle movement following the surface velocity

If you select “Bottom Velocity” in the same procedure, you can show the particle animation following the bottom velocity ads Figure 123 . Figure 123 :Particle movement following the bottom velocity